Here is the potential fatal flaw in the variation 8.Ne4 Ne6!? 9.Bxb5ch Bd7---10.Ba6!! (It took me months to find this concept---White maintains control over d3 & the retreat Bf1 allows White to play Ng3 while still defending g2). Here are three tries for Black
10...Ndf4 11.O-O Bc6 12.Re1 Nd3 13.Re3 Nef4 14.Qf3! Nxc1 (What else?) 15.Qxf4! & White is much better i.e. exf4?? 16.Nf6 doublecheck and mate!
10...f5 11.Ng3 Nc5 12.Bc4 Nb6 13.Bf1 e4?! (recommended by Fritz 8) 14.d4 exd3 e.p. 15.Bxd3 Nxd3 16.Qxd3 Qe7ch 17.Ne2 +/-
10...f5 11.Ng3 Nc5 12.Bc4 Nb6 13.Bf1 Qe7!? (A suggestion of GM Lev Alburt) 14.b4 Nb7 (Nca4 looks awful) 15.Ba6! Nd6 16.O-O f4 17.Nh1 Qg5 18.d4 Bc6 (Bh3? 19.Ng3+-) 19.f3 +/-
Thus, it would appear that 8...Ne6 is no better as an equalizing try than 8...Qh4.
The main line of the Fritz can be thought of as 4.Ng5 d5 5.exd5 Nd4 6.c3 b5 7.Bf1 Nxd5 8.Ne4 & the main tries are the Berliner Variation 8...Qh4 9.Ng3 Bg4 10.f3 e4 (The Berliner Gambit) 11.cxd4 Bd6 12.Qe2! (The Muir Variation). This is the winning move. 12...Bxb5ch is weaker.
First of all what doesn't work is 12...Bxg3ch? 13.hxg3 Qxh1 14.Qxb5ch +-
Black could also try 12...O-O, but is down too much material after 13.fxg4 Bxg3ch 14.Kd1 Nb4 15.Nc3 Rfe8 16.a3 Nd3 17.Kc2 c5 18.Nxe4 c4 19.Kb1 Rad8 20.Qf3 Nxc1 21.Kxc1 Rxd4 22.Nxg3 Re1ch 23.Kc2 Rxa1 24.Bxc4! Rxc4ch 25.Kb3+-
The second try by Black is even weaker: 12.Qe2 Be6? (Book---Now the blunder 13.fxe4?? which merely drives the Knight right where it wants to go is book!
If White had nothing better, then 13.Qf2 holding the piece is far complicated but winning for White.
Correct is 13.Nc3!! Game over! This is already +- 13...Nxc3 14.dxc3 Bxg3ch 15.hxg3 Qxh1 16.Qxb5ch Kf8 17.fxe4 Rc8 18.Bf4 c6 19.Qc5ch Kg8 20.O-O-O Qh2 21.Ba6 Rf8 22.d5 Qh5 23.Qxc6 +- Black has Bishop and three pawns for the Rook. From the starting position, it took Fritz 8 only 17 moves to Queen a pawn and win a Rook here.
In a post coming soon, I hope to address the critical variation, 8.Ne4 Ne6!?