Good question.  I believe the main line after 4...exf3 5.Nxf3 Bf5 is 6.Ne5, followed by g4 and Bg2.  Or perhaps, taking cues from Stefan Buecker's line of the Soller, simply 6.Bd3!? Bxd3 7.Qxd3 and again White is a tempo up on that line.

After 4...c6, how about 5.Bg5?  The potential pin on the f6-knight hinders Black's ...e5 ideas that are annoying for White in many other lines.

Some sample possibilities:
A.  5...Bf5 6.Bxf6 (else White ends up a pawn down for not much) 6...exf6 7.fxe4 Be6 8.Qd2 Bb4 9.Nf3 with roughly equal chances.  Black has slightly better development but I like White's two-pawn centre.

B.  5...h6 6.Bxf6 exf6 7.fxe4 with similar lines to variation A.

C.  5...exf3 6.Nxf3, followed by developing the bishop to d3, transposing to lines stemming from 4...exf3 5.Nxf3 c6 6.Bd3 Bg4, which arguably offers White more than 6.Bc4 Bf5.  Instead 6...Bf5 is probably not best in view of 7.Bd3!? Bxd3 8.Qxd3, when White has a useful extra tempo (Bc1-g5) on the Bf1-c4-d3 line mentioned above.  

In all of the above lines Fritz 10 likes ...Qb6 for Black, intending ...Qxb2, but in all cases White can prevent the capture on b2 with a2-a3, or make a Poisoned-Pawn style gambit of it with Qd2, Qxb2, Rb1, Qa3 which leads to very messy situations.

Yes, apologies for the mix-up!  The first move-order is 5...Nxe4 6.fxe4 e5 7.Nf3 (certainly not 7.Bc4 Qh4+) 7...exd4 8.Bc4, and while it might be an improved version for Black, I think White still has at least enough compensation for the pawn.

Instead 5...Nbd7 is about equal IMO, e.g. 6.Qd3 e6 7.Bf4 Nxe4 8.fxe4 e5.

But in any case I can't find a good continuation against 5...e5.

The line Stefan recommends- 3.Nc3 Nf6 4.f3 c6, has been debated on quite a few other threads.  I personally think 5.Nxe4 is good enough for equality- for instance 5...Nxe4 6.fxe4 exd4 7.Bc4, or 5...Bf5 6.Nxf6+ followed by 7.Bd3 and Black cannot win the pawn on d4.  However, there is a snag in 5...e5!?, when I can find nothing better for White than 6.Nxf6+ (I'm not totally convinced by the gambit 6.Bg5 exd4 7.c3 Be7) Qxf6 7.dxe5 Qxe5+ 8.Qe2, and a barren ending results. 

Instead, 5.Bc4 is the usual response but I doubt that it gives full compensation.  5...exf3 (5...b5!?- Bacrot) 6.Nxf3 Bf5 7.Bg5 (7.Ne5 e6 8.0-0 Bg6! =+) 7...e6 8.Qe2 works fine against 8...Be7 (9.0-0-0 and 10.Rhf1) but I can't find anything convincing against 8...Bb4!.  Perhaps White might be able to find something after 9.a3 Bxc3+ 10.bxc3 Nbd7 11.0-0 0-0.

Well, if you don't play d5, I will castle and slowly consolidate.
The Rh7 defends f7 in the meantime, it will reactivate later when I have a knight on f5.
My plan is to win the h4-pawn on move 60.

But the immediate d5 works, true.
On 13...Nf5 14.Qe2 g6, d5 again bails out.
Not so simple...

My first reaction is to play just 13...g6 from the diagram.
On 14.Fe5 Rh7, Fischer style.

Dark squares vs light squares, who will prevail ?
I still have my dark-squared bishop tho 

1.d4 d5 2.e4 dxe4 3.Nc3 Nf6 (3...f5!?; 3...Bf5!?) 4.f3 Bf5 (4...c6!) 5.fxe4 Nxe4 6.Qf3 Nd6 7.Bf4 e6 8.0-0-0 Nd7 9.g4 Bg6 10.h4 h5 11.g5 c6 12.Bd3

Uruk wrote on 02/24/09 at 22:22:51:


13. Rxd3! seems stronger (than 13. Qxd3).


In the BDG building up pressure on the f-file is one of the key ideas. The Rd3 might even participate in this plan, in some lines it could move to f3 or g3. If 13...Nf5 14.Qe2 intending g5-g6, or if Black plays g6 himself, the square f6 becomes weak. 


My BDG articles (Kaissiber 5 & 8) claimed that the traditional lines after 4...exf3 give White enough for the pawn, and there were many positions where I'd like to be White. But 3...f5 and 3...Bf5 (Morlo) were problematic, and since 1986 I believe that 3...Nf6 4.f3 c6! is the hardest nut for White to crack. 

Regarding another point in this thread, that it were better if young players would not learn the BDG. Here I am not so sure. Many creative players started with the King's Gambit (Steinitz, Tartakower [who later invented the BDG, by the way, so perhaps it should have rather be called the BTG], Reti, Larsen come to mind - and, of course, E. J. Diemer himself), later they changed their repertoire and preferred serious openings (OK, with one exception). I don't think that enjoying tactics in your younger years is a mistake, rather the opposite.  

Look at the great masters: Young Emanuel Lasker played 1.e4 e5 2.Nf3 d6 3.d4 Bg4 (? Kasparow: "Every schoolboy knows...") 4. dxe5 Nd7!?. And the young Capablanca even used the most irregular opening of his time: the Caro-Kann Defense...