Fashionable line of sicilian four knights

According to this blog post, http://www.qualitychess.co.uk/blog/7273

After

instead of 6...d6 inviting the Sveshnikov , black has the more fashionable line: 6…Bc5!? 7.Bf4 0–0 8.Bc7 Qe7 9.Bd6 Bxd6 10.Qxd6 Qd8.

(Of course there is the pretty solid traditional line 6...Bb4). I wasn't aware that 6...Bc5 was playable, doesn't anyone else know anything about it?

Has anyone bought https://www.bookdepository.com/The-Sicilian-Four-Knights-David-Willis-Vassilios-Kotronias/9781949859362?source=igodigital&utm_source=NL-Body&utm_medium=email-Newsletter&utm_term=button&utm_content=AUTOMATION&utm_campaign=AUTO_ABANDON_BRWSE, and is it any good?

Yes, this is quite a new development and might be worth a try. I usually played d6 in this position to transpose into the sveshnikov as Bb4 never really appealed to me.

I love the four knights which gave a countless of OTB wins or at least promising positions because my opponents rarely went for Ndb5 or for Nxc6 e5 and Ne4 which are just crazy moves to make if my opponent's never played against the Sicilian four knights before.

Are you aware of any other good resources? I more or less learnt it by playing it.

It seems like Robert Ris wrote articles in the chessbase magazine 201 and 202 on the newest developments in that Nxc6 line covering as 9. ...Qb6 as well as 9. ...Bb7 and 9. ...Rb8

Edit: ok it seems like Robert Ris published quite a bit of material on the SFK.

Thank you, wasn't aware at all of this possibility. It confirms impression given when Caruana avoided 6Nxc6 in candidates in a must win game, playing instead an unusal line involving Qd3 intending Qg3, that the sicilian four knights move order in good shape at the moment.

Have got the Willis book now. A bit disappointedly it covers mostly the old fashioned 6Nb5 Bb4, and the most highly analysed 6.Nxc6 bxc6 7.e5 Nd5 8.Ne4 Qc7 of the copycat games.  

Yes, I have checked out his analysis of 6Nbd5 Bb4 now, and it looks quite good, for example the Bg5 h6, and later Ne5 pawn sacrifice looks good for a draw. In general am happier in IQP positions than used to be, after looking at Tarrasch QGD a bit. Remember comment on Spassky games, in "Both sides of the chess board", that knights are good in IQP positions. In general 6...Bb4 looks a reasonable choice against ambitious players, and can keep  6...Bc5 for lower rated ones. 

#7
"Is 6.Nxc6 really the main line now? Has white nothing better, nothing more active?"
++ Most active is 6 Ndb5 d6 7 Bf4 e5 8 Bg5 transposing to the Sveshnikov, but where black has avoided the Nd5 variation.