CP3 is worth way too much. You're essentially giving up an early 1st rounder (CP3), late 2nd (Kidd), and late 3rd (Horford) for a late 1st (Amare), mid-2nd (Melo) and borderline waiver (Gordon).
I'm also not sure if it would help your team overall, since it looks like you're built around guards (assists, ft%, 3's, steals) right now. Your team looks really solid overall. I would look into moving Collison since TO's is another cat you could secure with that team. Your weaknesses are going to be FG%, blocks and boards, which the proposed trade wouldn't really help. By the way, his team looks like a mess with high injury potential.
It's a terrible offer for you. You do have far too many PGs I would think and if this guys needs one, you should be able to figure something out. You will win dimes every matchup, but it doesn't matter if you win by 40 dimes a week or 200. Right now you're overkill there.