The ideas 9.dxc5 and 9.Rd1 for white certainly seem promising. The OP is right that 9.cxd5 is definitely feeble by comparison. To be fair, this is a sub-line in a sub-line for Dembo, but only because she dismisses 6.Rc1 on the basis of 6...Be6! (her "!"). I guess 

I guess she really did not want to suggest something a bit passive like 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. e3 O-O 6. Rc1 dxc4 7. Bxc4 Nbd7 8. Nf3 c5 9. dxc5 Nxc5 10. O-O Be6 11. Bxe6 Nxe6 12. Be5 Qxd1 13. Rfxd1 Rfd8 14. Kf1, which does seem okay.
BobbyDigital80 wrote on 07/10/10 at 20:23:32:

It looks like reasonable compensation to me. White is behind in development, his king is still in the center etc. In fact it is a lot like 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. e3 O-O 6. Rc1 c5 7. dxc5 Na6 8. cxd5 Nxc5, except that in exchange for the non-developing move b6 white played Qb3, so that Na6-c5 will happen with a tempo. E.g.
1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. e3 O-O 6. Rc1 Be6 7. Qb3 b6 8. Nf3 c5 9. dxc5 Na6 

A. 10. cxb6 Nc5 
A1. 11. Qb4 Qxb6 12. Qxb6 axb6 13. Nd4 dxc4 14.
Nxe6 Nxe6 15. Bxc4 Nxf4 16. exf4 Rfc8 17. b3 Bh6 18. g3 e5 19. Rd1 exf4 20. a4 fxg3 21. hxg3 Bf8 and this surely is okay and throughout I kind of feel I'd rather be black with his initiative.
A2. 11. Qc2 dxc4 12. b7 Nxb7 is probably a sensible try for white to avoid getting into any trouble, but surely this is fine for black.
B. Another interesting idea is 10. c6, where I analyzed around a bit, but am not 100% sure about what to make of it, e.g. in the line I analyzed below white seems to end up being a bit better: 10...dxc4 11. Bxc4 Nc5 12. c7 Qd7 13. Qb5 Bxc4 14. Qxc4 Nd3+ 15. Ke2 Nxf4+ 16. exf4 Rac8 17. Ne5 Qxc7 18. Qxc7 Rxc7 19. Nb5 Rxc1 20. Rxc1 Nd5 21. Nd3 a5 22. Rc6 Nb4 23. Rxb6 Nxd3 24. Kxd3 Bxb2 25.
Kc2 Bg7 26. Ra6 which actually looks pretty promising for white.

And of course there is 9. Rd1 Na6 10. Be2, which I actually like beter for white than 9.dxc5.

gewgaw wrote on 07/10/10 at 10:27:41:

I'm not "still reading" the book. I occasionally check her book out of curiosity if I'm wondering about a specific line. I don't trust anything she says though. 9.dxc5 Na6 and black sacrifices a pawn for what?

BobbyDigital80 wrote on 07/10/10 at 05:27:25:


A couple of months ago, you blamed dembo´s book being crab, so why on earth you are still reading it 
By the way, after 9. dc5 Na6!? looks interesting.

Dembo gives this line as good for black 1. d4 Nf6 2. c4 g6 3. Nc3 d5 4. Bf4 Bg7 5. e3 O-O 6. Rc1 Be6 7. Qb3 b6 8.Nf3 c5. And then she says 9. cxd5 Nxd5 10. Nxd5 Bxd5 11. Bc4 Bxf3 12. gxf3 cxd4 13. Bd5 Na6 14.
Bxa8 Qxa8 gives black the initiative. But why on earth would White play 9.cxd5? After 9.dxc5 or 9.Rd1 white is just better. Of course white will isolate the pawn on c5 and then play against it. This is just really simple play for White which seems to lead to a clear edge. Dembo doesn't understand what a bad pawn structure is.