Rizzitano thinks Black's best after 5. Bf4 dxc4 6. e4 is a straight transposition to the Vienna QGD with 6...Bb4 7. Bg5. If Black wants to play dxc4, he could have done it on move 4.

I am not impressed by 4... Nbd7. While it is unclear if 5. cxd5 cxd5 6. Bf4 is any better than a normal Bg5 Carlsbad, Black is already giving up the option of playing the Alatortsev move order (3... Be7), the option of playing the Tartakower amongst others. That's too much to give up just to avoid 5. Bf4, unless Black is already well versed in say, the Cambridge Springs.

Gelfand-Graf Plovdiv 2003 is a good demonstration of White's prospects after 5. Bf4 anyway :

1.d4 Nf6 2.c4 e6 3.Nf3 d5 4.Nc3 Nbd7 5.Bf4 dxc4 6.e3 a6 7.a4

Nb6 8.a5 Nbd5 9.Bxc4 Nxf4 10.exf4 Be7 11.O-O O-O 12.Ne5 Qd6

13.Re1 c6 14.f5 exf5 15.Nxf7 Rxf7 16.Qb3 Nd5 17.Nxd5 cxd5

18.Bxd5 Qf6 19.Rac1 Bd7 20.Rc7 Rd8 21.Rxb7 Kf8 22.Rb6 Qxd4

23.Bxf7 Bc5 24.Rd1 Qxf2+ 25.Kh1 Be8 26.Bd5 Bh5 27.Ra1 Qf4

28.Rxa6 Bd6 29.Rxd6 Rxd6 30.Qa3 Qe5 31.a6 Qxd5 32.a7 Kf7

33.Qxd6 Qxd6 34.a8=Q Be2 35.Qa7+ Kf6 36.Qa3 Qd5 37.Qe3 Bb5

38.Re1 Bc6 39.Qe7+ Kg6 40.Qe6+ 1-0