Still Strange, Still Intriguing (Part 2)

Continuing with my historical review from earlier coverage in this blog on the following position:

At the beginning of 2010, in "Opening Reports on the New Year's Database [a fore-runner of The Database]" I reported

I re-ran the Opening Report on 1.e4 e5 2.Nf3 Nc6 3.Bc4 Bc5 4.Bxf7+ Kxf7 5.Nxe5+, and noticed that White scored 74% against 5...Ke8; 67% against 5...Ke7; 53% against 5...Nxe5; 45% against 5...Kf8; and 38% against 5...Ke6.

That last statistic got me interested again in following down what I called "A Strange But Intriguing Path (Part 1)" (where I looked at the natural, but not best response, 6.Nxc6):

[5...Ke6] What an odd move! Yet, there are 10 examples in the New Year's Database, and White only scored 30% in those games. As I've noted, this bears examination.

A further look appeared in "A Strange But Intriguing Path (Part 2)"
where, in addition to the troubled 6.f4, I looked at a couple other lines for White:

Inadequate is 6.Nc4 Qf6 (6...Qh4!? 7.Qe2 Nd4 8.Qd3 Nf6 [stronger than 8...Nxc2+ 9.Qxc2 Qxf2+ 10.Kd1 Qxg2 11.Re1 Qxh2] 9.Nc3 d5 10.exd5+ Kf7 11.Ne3 Re8 12.Ne2 Rxe3 13.dxe3 Bf5) 7.Qg4+ Ke7 8.0-0 h6 9.Nc3 d5 10.Nxd5+ Black resigned, jecree - larsgoran, FICS,  2008 

Tricky is 6.d4, as the pawn is poisoned, provided that White responds to either 6...Nxd4 or 6...Bxd4 with 7.Qg4+ (7.Nf3 may draw). 

After 6.d4 Nxe5 (6...Nf6 is best met by 7.Nf3 with an edge to White) 7.dxe5 d6 (7...Kxe5? 8.Qd5+ Kf6 9.Bg5+ Kg6 10.Qf5+ Kh5 11.g4 checkmate) 8.Nc3 Black has an edge. 

In "A Strange But Intriguing Path (Part 3)" I tackled what is possibly White's strongest response to 5...Ke6:

6.Qg4+ Kxe5

If White is going to have a chance in this variation, he must sacrifice the second piece. If Black then wishes to play on, he must accept the piece.

If 6.Qg4+ Kf6, then 7.Qf5+ Ke7 8.Qf7+ Kd6 9.Nc4 checkmate. 

If 6.Qg4+ Kd6 7.Nf7+ wins.

If 6.Qg4+ Ke7 7.Qxg7+ Kd6 8.Nf7+ wins.

7.d4+

[to be continued]