How's this for a sound theory dodge that's also remarkably aggressive?

why 8. Bf8??????

The blitz player in me wants to sac the exchange on h5 for some compensation

---

This was my thought as well.  As soon as that knight takes up residence over there, the rook is as good as sac'd.  It's just like the Nakamura line against the Leningrad.

Bf8 is to stop g4! from winning the knight. I think the knight can be subjected to further abuse, because to re-enter the game it will have to go to g7, and then make a square available for it. After Ng7, I think Bh6 will continue to tie down Black's pieces, and white may well be much better.

It certainly has potential.

If Black intends to take on h5, though, then 4...Bg7 is just wasted because of your line.  But what would Black do instead?

And what about 4...h5?! Or is that suicide? You can always castle queenside later in the game if you want...

4. .... c5 and White's h4 looks a little out of place.

Now that I look at it, I think a rook sac may be premature, because I think black may be able to consolidate with correct play.

I also think Prawn may be right on this one. If black counterattacks at the center, white's h4 looks sorta useless. 

Also, I think 4... h5 is interesting, but it may be too committal and black might be better off with ...c5 or simply ...Bg7

4...c5 does seem like an interesting idea, but I can't find too many games steming from either.

On 4...h5 it seems like both White and Black have wasted a tempo, but now moves like Bg5 seem much more annoying?

With 4....Bg7 I feel white will definetly have enough for the pawn, but if you'd like to provide a line where you're doubtful I'd be glad to share analysis.

With that in mind, here's my take on how the 4...c5 line would continue...

In the OP analysis, why do you take the h5 pawn ? It surrenders in the center.

6....c6 or Bf5 seems me better.

---

Black has the f-file, and should have a reasonable game (or at least so it seems as I look at it, feel free to correct me if I'm wrong). However, I'm not saying this is better than c5. I feel c5 might be even better, but I do believe Bg7 is better than h5, because of the g5 weakness.

Personally, I believe c5 is significantly better, and may give black an advantage.

Continuing from your line:

 

I see, white doesn't have to take on g6. However, in my previous analysis above, h6 simply allows black to drop the bishop to h8 and have a very comfortable game from the wasted tempi used on the h-pawn

You make a valid point. I might even prefer ...h5 to that line, but I believe you are correct and that ...c5 is best.

The point of h6 would only be to push the bishop back to f8, where black has wasted as many tempi as white. After O-O, hxg6 is the correct move I believe and have added some analysis on that line.

The newest on 4...c5:

What about c6 right after h4? I think this works well for black.

The idea behind h5 is either to:

Deflect the knight so White can take the center

Take on g6 to inflict a weakness

push to h6 so that the g7 bishop is pushed back to f8.

 

In the instance where it can do none of these, there is no point sacrificing both the pawn, and the extra tempo. As a side note, I'm pulling games from Chessbase's Database for the openings, but there isn't much on c5. As far as c6, there are 48 games featured. Most continued: