Current theory says that black is clearly better in the moeller attack cause of 13.... h6 but I think a new move 14. Qb3! gives white enough compensation for the sacrificed pawn and a good game.
This long line is more or less forced
1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4 exd4 6. cxd4 Bb4+ 7. Nc3 Nxe4 8.
O-O Bxc3 9. d5 Bf6 (Ne5 also possible) 10. Re1 Ne7 11. Rxe4 d6 (0-0 is interesting alternative)  12. Bg5 Bxg5 13. Nxg5 h6! (0-0 draws here, IF black knows all his lines, which rarely is the case) 

Here two moves have been extensively analysed, 14.Qe2 but after hxg5 15.Re1 Be6 16. dxe6 f6 17.Re3!? c6! 18.Rh3 Rxh3 19.gxh3 g6 in this position white has tried lots of moves but the simple plan for black to play Kf8 and Kg7 gives black clear advantage.
The other move 14.Bb5+ which actually is old refuted main line had a revival with Bd7 15)Qe2 Bxb5 16)Qxb5+ Qd7 17)Qxb7!? where it was thought that white had some compensation but this line is refuted now also cause of 0-0 18)Rae1 and now not Ng6 but the much better Rab8! giving black winning advantage.

But now a new move has been found on the fantastic website on this opening http://sorrowdy.mysteria.cz/.
The move is 14.Qb3! with the idea that after hxg5 15.Rae1 Be6? white can play 16.Re3! with the idea that after 16. ... c6 17.dxe6 f6 18.Rh3 black can't take the rook cause white can now take back with Q in contrast to the 14.Qe2 line.

After 14.Qb3! hxg5 15.Rae1 Kf8 16.Qe3 seems at first glance to be at least good enough for equality.

So 14. ... hxg5 doesn't seem to give anything but normally if black can castle in these kind of lines he gets tempo cause knight has to return and black gets the advantage.
But here I believe that also after 14. ... 0-0 white gets compensation for the pawn after 15.Rae1 (or maybe immediately 15. Nf3) Ng6 16.Nf3.
Now I don't really see a move that gives black advantage. Whites compensation is in the fact that a) he totally controls e-file b) he gets a strong square for his knight on d4 c)black has troubles developping his bishop due to the pressure of the queen on b7 and black can't really sacrifice b7 pawn cause then in most lines Qxb7 Rb8 Qa3 Rxb2 is not possible cause of Bb3 which traps the rook on b2.

I'm convinced this line is an improvement over the current main lines, not that I think black isn't ok but white seems to have enough compensation to reach equality.

And if this is true then it seems that the guioco piano moeller attack (after 7.Nc3!?) leads to draw in all current known lines which would make it a opening weapon that you can't lose with but only win if black isn't aware of the theory.