the diagonal for the queens bishop is opened after exd5. also, the e pawn doesn't function to protect the king; you're going to want to castle. either is probably fine, though, from what I can see.
better for white might simply be the developing moves 4. Ngf3 followed by 5. Bd3, 6. 0-0, 7. e5 (rather than capturing) depending on what you do to respond.
I, however, don't know too much about the colle from black or white's perspective.
Hi!
I'm recently experimenting with the Colle (Koltanowski and Zukertort) and I found that I can play similar openings that lead to similar situations with black, playing the Slav against d4 and the Caro-Kann against e4. While practicing, the following line came up:
1. e4 c6 2. d4 d5 3. Nd2 e6 4. exd5
I couldn't find this line in any databases, there are 76 games until e6 but in the next move they come up with different moves maybe because taking the d5 pawn is not a good idea for white. Anyway, the question is, after 4. exd5, with wich pawn should I take? cxd5 or exd5? Toga II suggests cxd5 but Toga II doesn't have preference for Colle similar games. I personaly think that I should play exd5 that protects the king and opens the diagonal for the queen's bishop but, who am I?