This is not best. Black loses a tempo avoiding the fork Ne6+.

I prefer 8....Kc6 but both moves have there ups and downs. I have to admint that 8...Kc7 is statisticly the best move But there is 1 other move possible 1 that ends the game by 3 fold repetition. But that would be a big waste, i hope nobody will play it (and so far so good.. )

My advise on 9....Qd5 is do not play it. after 10.Nc3 Qc6 you where lucky that Dmeastro wasted tempo by moving 11.0-0 instead of 11.Ne6+ after that en if played well you wil be 2 steps behind of everything.

This would already seem to cast doubt on Black's idea. But real the test is yet to come.

True. But White could test the security of Black's Royal family by 11.Ne6+! Let's give a "for instance": 11.Ne6+ Kd6 (suppose) 12.Nd8 Qe8 (to cover f7) 13.Nxe4+ Kd5?? (13...Kc7 is safer, but Black's game isn't looking too bright) 14.Be6!! and now White has a forced mate: [A] 14...Kxe4 15.d3+ Kd4 16.Bc4 and 17.c3# or [B] 14...Kd4 15.Nf2! c4 16.Nxb7! any 17.c3#. This is not to say 11.Ne6 is winning. Not at all. But it seems likely to give Black a much rougher time of it.

And when you're down a peice in return for the attack, you musn't give the opponent time to catch up.

Both above spoken well  

But opening lines at the same time. Then again, you have to free your position somehow.

See how much time White has lost going after the h8-rook. Black's game is looking very good now. I've not often seen such volatile games as this Grand Prix Attack gambit line seems to produce. Two moves ago I felt sure that White had the better of it (slightly).

That's why this line is so interesting   Both sides have to play patient. White needs to keep the pressure on and stall black from developing pieces whiteout trading pieces. Black has to wait and wait for white to develop a piece or trade a piece. black gains strength every time a piece is traded or if white spends time for a capture or a developing move this also means that if black try,s to attack or develop pieces white gains momentum.. A thin line to walk on for both sides.

In this position, 15...c4 looks strong, clearing c5 for the bishop and thus threatening to take the knight, or even better, place the Queen on e2 with mate almost certainly to follow, e.g. 16.Nf7 Bc5+ 17.Kh1 Qe2 18.h3 Qxf1+ 19.Kh2 Bg1+ 20.Kh1 (20.Kg3 Qf2#) Bf2+ 21.Kh2 Qg1#

15.Be6 is just a bad move.. i can see why Dmeastro moved it. but after 15....exf4 white is in big trouble. good for white that Rob discovered it a move to late...

I feel sure this capture would have been much stronger a move earlier: 15...fxg4 16.Bb3 c5! 17.Ba3 Bc5+ 18.Kf1 and Black can calmly take the knight on h8, or go for the throat with 18...Qe2! (19.Rg1 Ng5 should give a winning attack).

Why the need for the 15th move?

I think I was still obsessed with development. You're probably right. It was unnecessary at this point.

There's more to this move than mere distraction! White threatens 19.Bxf4+, which, by the way, precludes any idea Black might have had, after 18...Qd4+ 19.Kh1, of resuming his double attack by 19...Qe5.

20.Bg4! wins (I think) material due to the threat of Ne6+

Maybe you had the position wrongly set up. 20.Bg4 won't do, on account of 20...Bxg5 (the f6-Knight having just moved off) 21.Bxh5 g6 and Black's material edge and more active game should guarantee a big advantage.

20. Bg4 Bxg5 21. Bxh5

I would play 20.Nf3 the Lady will move to the logical place 20....Qf6 and then i would play 21 .Bd5

Now that both sides have their forces fully deployed it is hard to see who might have the advantage. The position is complicated and quite obscure.