I'm only a few years late with a reply, but here goes.

Firstly, I think we should remember that white is playing a dubious gambit here - so if he gets to equal and unbalanced positions, then this is a success for the gambit. Thus, continuing your line after 11...Nc6 (I agree, black can happily go in for the line of taking on e4), 12.d5!? O-O-O (12...Nb4 is also playable) 13.dxe6 Bg7 14.Qxd8+! Nxd8 15.Nge2 Qxe6 16.O-O Qc4!? 17.Ng3 gives a very interesting position where white has two rooks for the queen, but will probably need some time to get his pieces into play, and may well need to give up one or two queenside pawns to achieve this. The flip side is that black will be opening up files for the rooks if he takes pawns on the queenside... the position looks unbalanced and white looks fine. Not winning, but after 2.e4 I think we shouldn't ask too much.

If this isn't to your taste, white has a very nice alternative in 5.Ng5, where after 5...Qxd4 6.Qxd4 ed 7.Bc4! the position is very reminiscent of some lines of the Falkbeer Countergambit (a response to the King's Gambit) with colours reversed, and the oddness of it being the queen's knight on g5 instead of the king's knight! I think this favours white - the other knight can come to e2 and f4 eyeing e6 and g6 (thus making h6 unpleasant potentially), the d4-pawn will be soon targeted by N1/5f3 and O-O-O. This would be my choice OTB if someone was foolish enough to play 4...f5... 4...Qxd4, 4...exd4 and 4...Nc6 are all far better moves, and it is these you need to worry about if you plan to resurrect this line.  (I personally play the 4.Qh5 line, though I throw this in occasionally)