4.g4 is an interesting idea, which I was completely unaware of, despite having Martin's 'The Contemporary Anti-Dutch'.
A look in the base reveals that it does have some poison indeed, however, I think 4...Bb4!? may be the way to go for black.
Here's a few examples:
Thuesen,M (2250) - Hansen,S (2355) [A80]
DEN-chB playoff Denmark (1), 1991
1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.g4 Bb4 5.gxf5 exf5 6.Qd3 d5 7.0-0-0 0-0 8.Bh3 Bxc3 9.bxc3 Qd6 10.Bxf6 Rxf6 11.Nf3 Nc6 12.Ne5 Nxe5 13.dxe5 Qxe5 14.Qxd5+ Qxd5 15.Rxd5 Be6 16.Rd4 Re8 17.Bg2 c6 18.Bf3 Kf8 19.a3 Ke7 20.Rg1 Rf7 21.Rh4 g6 22.Ra4 a6 23.h4 Kf6 24.Rd4 Rd7 25.Rgd1 Red8 26.Kb2 Ke5 27.e3 Bd5 28.c4 Be6 29.c3 h6 30.Kb3 Rxd4 31.cxd4+ Kd6 32.Kb4 b6 33.c5+ Kc7 34.cxb6+ Kxb6 35.Rg1 Bf7 36.Ka4 Kc7 37.Rb1 Bc4 38.Ka5 g5 39.hxg5 hxg5 40.Rh1 g4 41.Rh7+ Rd7 42.Rxd7+ Kxd7 43.Bd1 Kd6 44.Bc2 f4 45.exf4 Kd5 46.Kb6 Kxd4 47.Kxc6 Kc3 48.Bd1 Be6 49.Kd6 Bc8 50.Ke5 Kd2 51.f5 1-0
Buckley,G (2385) - Mellado Trivino,J (2470) [A80]
Mondariz 04 Mondariz (2), 1996
1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.g4 Bb4 5.Qd3 d5 6.gxf5 exf5 7.Bh3 h6 8.Bd2 0-0 9.Nf3 Ne4 10.Rg1 Kh7 11.0-0-0 Bxc3 12.bxc3 Qe7 13.Rdf1 Qa3+ 14.Kd1 Qxa2 15.Bc1 Bd7 16.Ne5 Ba4 17.f3 Nd6 18.Rg2 Bb5 19.Qe3 f4 20.Qg1 Rg8 21.Bxf4 Nc6 22.Nxc6 Qa1+ 23.Bc1 bxc6 24.Qe3 Rae8 25.Be6 g5 26.c4 Rxe6 27.Qxe6 Qxd4+ 28.Ke1 Bxc4 29.Be3 Qg7 30.f4 Re8 31.Qh3 Qc3+ 32.Kf2 d4 33.Qd7+ Kh8 34.Bc1 Rxe2+ 35.Kg1 Rxg2+ 36.Kxg2 Bxf1+ 37.Kxf1 Qf3+ 38.Ke1 Qh1+ 39.Kd2 Ne4+ 40.Kd3 Nc5+ 0-1
Sebih,K (2375) - Mellado Trivino,J (2395) [A80]
Casablanca Casablanca (6), 1994
1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.g4 Bb4 5.gxf5 exf5 6.Qd3 d5 7.0-0-0 Bxc3 8.bxc3 0-0 9.Nf3 Qd6 10.Bxf6 Rxf6 11.Ne5 f4 12.Bh3 Nc6 13.Bxc8 Rxc8 14.c4 Re8 15.Rhe1 Rfe6 16.cxd5 Qxd5 17.Nxc6 Rxc6 18.Kb1 Rh6 19.e4 fxe3 20.fxe3 Rxh2 21.e4 Qe6 22.Re3 c6 23.Rde1 b5 24.R1e2 Rxe2 25.Rxe2 h5 26.e5 Rf8 27.Rg2 Rf5 28.Qg3 g5 29.Qa3 g4 30.Qxa7 Rf7 31.Qb8+ Kh7 32.Rh2 Rf5 33.Qc7+ Kg6 34.Qd8 g3 35.Rg2 Rg5 36.Qf8 h4 37.Qh8 h3 38.Rg1 g2 39.Qh4 b4 40.Kb2 Qg4 41.Qf2 Rf5 42.Qd2 Rf1 43.Qd3+ Qf5 44.Qg3+ Kh5 45.Rxg2 hxg2 46.Qh2+ Kg6 47.Qxg2+ Kh5 48.Qh2+ Kg4 49.Qg2+ Kh4 50.Qxc6 Qf4 51.Qf6+ Qxf6 52.exf6 Kg5 53.c3 bxc3+ 54.Kxc3 Kxf6 55.a4 Ke6 56.Kc4 Kd6 57.a5 Rb1 58.d5 Rb2 0-1
Pruess,D (2345) - Pixton,A (2445) [A80]
ch-USA, Seattle USA (5), 2003
1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.g4 Bb4 5.gxf5 Bxc3+ 6.bxc3 exf5 7.Qd3 h6 8.Bxf6 Qxf6 9.Bg2 Nc6 10.e3 0-0 11.Ne2 b6 12.Nf4 a5 13.Rg1 Ba6 14.c4 Qd6 15.a3 Kh7 16.h4 a4 17.0-0-0 Rae8 18.c5 Qxf4 19.exf4 Bxd3 20.Rxd3 b5 21.Kd2 Na5 22.Rg3 Nc4+ 23.Kc3 Nxa3 24.Bf1 Rf7 25.Bd3 Nc4 26.Ra1 d5 27.h5 Re6 28.Rag1 Kg8 29.Rg6 Ref6 30.Re1 Kf8 31.Re6 Rxe6 32.Rxe6 Rf6 33.Rxf6+ gxf6 34.Bxf5 Ke7 35.Bd3 c6 36.Kb4 Kd7 37.Bxc4 dxc4 38.f5 Kc7 39.c3 Kb7 40.Ka3 Ka7 41.Kb2 Ka6 42.Ka2 b4 43.Kb2 Kb5 44.Kc2 a3 45.f3 Ka5 0-1
By the way:
Quote:1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.e4 (also leading to a good game, albeit apparently not covered in the book.)
I've been under the impression that 3...e6 was bad due to 4.e4 'with a good Staunton gambit', but found to my surprise that Pinski actually recommends this for black in his book on the classical dutch, giving the game Höi-Piskov Copenhagen 1991 as example.
And if the dutch experts below play it, it may just be that black has easy equality here!?
Palatnik,S (2460) - Malaniuk,V (2560) [A83]
Kiev Kiev, 1989
1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.e4 fxe4 5.Nxe4 Be7 6.Bxf6 Bxf6 7.Nf3 Nc6 8.c3 b6 9.Qa4 Bb7 10.0-0-0 Qe7 11.Nxf6+ Qxf6 12.Ba6 Bxa6 13.Qxa6 0-0 14.Qd3 Qf5 15.Qxf5 Rxf5 16.Rd2 Raf8 17.Re1 g5 18.Ree2 ½-½
Temirbaev,S (2480) - Jussupow,A (2665) [A83]
Yerevan ol (Men) Yerevan (7), 1996
1.d4 f5 2.Nc3 Nf6 3.Bg5 e6 4.e4 fxe4 5.Nxe4 Be7 6.Bxf6 Bxf6 7.Nf3 d5 8.Nxf6+ Qxf6 9.c3 0-0 10.Be2 Nc6 11.0-0 a6 12.Qd2 Bd7 13.Rae1 ½-½