5.Nxf7, 6.Kf1, 9.d6, 10.Bf7+

I've recently played a game using what seems to be the Traxler's main line in the Nxf7 variation(1.e4 e5 2.Nf3 Nc6 3.Bc4 Nf6 4.Ng5 Bc5 5.Nxf7 Bxf2+ 6.Kf1 Qe7 7.Nxh8 d5 8.exd5 Nd4 9.d6 Qxd6), and my opponent played 10.Bf7+, which I have not found in the forums. 

Here, Black has 4 choices:

• 10...Kf8 seems the safer move in the position. In my game, we followed with 11.Bc4 Ne4 12.c3 Nf5 13.Qf3 Qc6 14.Qxf5??, where he blundered his queen. I have not been able to find an improvement for white in this line till move 14.
• 10...Kd8 is the other "safe move" in the position, but after 11.Bc4 white can get his Knight out of the corner with check, thus saving it.
• 10...Ke7 looks more risky. I haven't still haven't looked deeply at this position.
• 10...Kd7 seems to be the weakest move in the position. It blocks the c8 bishop and after 11.c3 black's Knight is forced back and white can move 12.Qb3, which does not look good.

First, 10.Bf7+ doesn't look right. Blacks most principled reply is surely 10...Ke7 when white's last move looks like a waste of time. IMO white is in serious trouble, as black is threatening ...Bg4, and both the moves that prevent it (11.h3 and 11.Bh5) run into 11.Bh4 with terrible threats.

10...Kd7 is a blunder: White can take the bishop on f2, when 11...Ng4+ is no longer possible, and 11...Ne4+ 12.Ke1 (threatening Qg4+) is simply losing for black.

10...Kd8 is also a very weak move, after 11.Bc4, or probably 11.Bh5

10...Kf8 is not so bad, but white can probably make some developing move (at last!) with 11.d3.

So, black should be fine here. Too bad that 5.Bxf7+ or even 5.d4!? spoil all the fun for him...