Switching to 1...e5

If you are a beginner playing 1...e5, be prepared to face the Parham Attack a lot of times (2. Qh5).

After people realize they just wont children's mate you, nor take your rook, they start to shift to the traditional oppenings. 

Switching openings won't improve the quality of your chess play. The best way to do that is to practice with for example the excelent series chess evolution of Jussupov (http://www.newinchess.com/Chess_Evolution_1-p-7017.html)

In a way strategic concepts (like development, piece placement en the center) in e5 openings are easier to grasp than in other openings. So it is easier to play these openings in the strategic correct way. 

When i switched i had a lot help from this dvd http://chessbase-shop.com/en/products/gustafsson_vol2_open_games though i would say it is about 1600 up. 

all you'll get to play anyway are boring italian games.

I think the Sicilian family is better practice because they're more dynamic, with more tactics and more opportunities for various imbalances. 1.e5 usually gets into comparatively stale, mirror-ish games.

Lines I always have problems with

1. Ruy Lopez- Berlin defense (the marshall attack is fun, but defendable)

2. Classical King's gambit accepted

I never play the scotch or italian so I don't know. Not a lot of people play the scotch though.

@moonie, I have quite different opinion but I am just a patzer (compare our blitz ratings to see why)

If you do not play 1.e4 with white then switching to 1...e5 can help you understand and practice open games which is a very important part of chess.

Open play teaches you the basics of openings like the importance of development, space and activity.

When you play e.g. Sicilian scheveningen you are waiting on the last 3 ranks and prepare for counterattack. In 6.Bg5 lines of Najdorf black is sometimes safer with his king on e8 - both strategies have no chance to work in open positions (well, the first is employed in Philidor defence but this is just an exception to the rule).

Though the majority of open games are strategically easier to play there is one notable exception. The Ruy Lopez is one of the most strategically difficult opening with tons of different ideas and decisions. White has to choose between them wisely and black's role is to carefully prepare to meet them. I do not know any Sicilian line which would involve such a wide spectrum of strategic ideas.

I like the Modern Steinitz fianchetto (Bronstein) variation against the Spanish and it took me a long time to find it. I don't think it's what I lot of players with White like to see/are used to seeing, and it's good. Black will play similar to KID mostly going for an f5 break which I like to do. Of course there are earlier ways to play f5 against the Ruy which I've messed with but they get much sharper and it's more theory than game, or anyway not to my liking as much as this line. It's outlined in Tim Taylors "Slay the Spanish" along with a few other systems in the Modern Steinitz (Siesta variation, etc...) obviously there's a lot of other good stuff out there... Marshall, mainline, Archangel, depending on your taste, but they're all a complicated mess of theory. I find the Steinitz with the Fiancetto took me a little time to learn but it super reliable and I always get a position I can enjoy playing. 

For most of the rest I can recommend Emms Play the Open Games as Black. I don't play all of his recommendations anymore but I think they're good. Maybe at the highest level the 2 knights is shaky these days? But at my level at least it's a good way to fight to win with black and mainly it just avoids all those "boring italian games" mentioned above. It's probably the most useful chess book I own, coving just about every major 1. e4 e5 line for Black except the Spanish... the Parham is not there either, though that one is not challenging at all. I like to play 2... Nf6 in Blitz or Nc6 too depending on my mood; both should be good for equality or more... (...Nf6 gambits a pawn and can get very sharp but it's good) anyway it has the ones you're asking about plus Vienna, Danish, 4 knights, etc... I actually play Bc5 against the Scotch instead of Emms recommendations (which start with Nf6) but his line seems really good... I just learned the other one first.

@dzikus: You do not become better in understanding the game by just playing the opening. You have to analyze en see where you went wrong. Why you went wrong and how you could improve. However at lower levels the mistakes that lose the game are often not related to the opening and thus you gain no new understanding by seeing that you dropped a piece 3 moves after your theory ends. Instead of you want to improve it is better to look at the books I recommended. I still use chess evolution a lot too ! 

@Assault: At chess.com i seem to get quite a few italian game. In OTB it seems only about 20% of my games. I also do not think they are boring btw :)

Personally i play:

• Ruy Lopez - Berlin 
• 3. Bc4 - Italian (the 2 knights are perfectly fine if you like the tactical weird positions)
• Evans gambit - Be7 
• Scotch - Nf6 (Bc5 is ofcourse fine too but Nf6 is easier in the many weird Italian/Scotisch gambit type transpositions) 
• Kingsgambit - exf4 and g5

A good idea for a beginning player is 1. e4 e5 2.Nf3 Nf6. (Petrov's defence)

It avoids the Ruy Lopez, the italian, the scotch and he evans and steers the game into your territory instead of your opponent's.

Against the KG I recommend the countergambit 1.e4 e5 2.f4 d5!? 3.exd5 (fxe5?? Qh4+ either mates or wins the rook in the corner) c6 4.dxc6 Nxc6, where white still cannot take the pawn on e5 and after exf4 black is in good shape.

Leave me a post on your wall if you want me to explain some things about the petroff's defence

I suppose Davies Play 1. e4 e5! is a good place to start.

That would involve the Keres with 12...exd4.

Declining the King's Gambit

The Two Knights

and 3...Bc5 against the Scotch.

Of course you still need to analyze your games to actually improve, but I would suggest some sort of repertoire book to help make the switch. 

Is it worth the switch, though?

I'm quite content with playing the sicilian, but am just curious on whether switching to e5 will improve my chess understanding.

Stay with 1...c5.  Of course I'm biased, having always preferred the sicilian variations.  Why play ...c5?  If White chooses to play the open sicilians you get the opportunity to steal the initiative and fight for advantage early on in middlegames regardless of whether you play 2...d6, Nc6, or e6.  Of course White also has the ability to blow you off the board if you don't know vital ideas in certain positions, but naturally with more play/study you will learn these ideas.  Plus many White players have the misguided thought that the "anti-Sicilians" are actually anti-Sicilian, when in fact all those variations are less challenging for you as Black compared to 2.Nf3 and 3.d4.    

Just play and study all kinds of openings! And have one to three ''main'' openings! 

No it will not increase your chess understanding. Nor will playing the Sicilian or the Semi-Slav. 

Is it worth your time? You know the value of your time more then me. Both 1...c5 and 1...e5 can take up a lot of your time. You can't know which one is better for you personally until your opponents are good enough to challange you in the mainlines.

Moonnie already said all there is to say on the subject.

Don't know about this..

It's true that switching openings won't improve your rating, in fact it'll probably drop at first. If I could start my chess 'carreer' all over again I would have switched openings a lot early on though. Just to get familiar with all the different structures and typical ideas.

Like i said before. If you want to better understand positions get a series like Chess Evolution from Jussupov or a book like My System (Nimzoitisch) instead of learning opening moves without understanding the concepts explained in these books. You will learn faster and lose less rating in the process. 

Moonnie, but Yusupov advises to switch to the Petroff ( 1. e4 e5 2. Nf3 Nf6 ) in his series.

I was playing the Sicilian before I started training with Yusupov, and I do think that my game improved immediately with playing the Petroff (all I did was follow the ideas in Yusupov's lesson, no real study or memorization of the opening).  It is just a that it is a very simple opening which leads to simple but solid positions, there is not too much to learn.

Also, beware that Chess Evolution is not the whole series, the series itself is 9 books (Build Up Your Chess 1-3, Boost Your Chess 1-3, Chess Evolution 1-3) ... I think just following the Chess Evolution titles would leave some gaps.

My advice is to learn the 1...e5 with black first. It will teach some basic ideas that will take place in many opening and positions eventually. Then learn the Sicilian. I also recommend sticking with an opening once chosen. It is the best and fastest way to improve you level of play. If you are a master of one white opening and 2 or 3 black defenses, even if you aren't the best raw tactician or strategist, your level of play will supercede it to a point.

The openings don't help much in the middlegame. The whole familiarity argument can only hold for so long because soon tactics and other considerations will force a change in the game. And then there is the chance that the opening goes in a direction you've never encountered.