I think so... Upton's been ridiculous, but only with no one on base... Call me crazy, but his splits with and w/o RISP scream "choker." But that might be just me, and he very likely might get enough chances in non-clutch situations to be a huge asset. But Braun? Yeah, you gotta.
We could see the team but I don't know what it could change. I would probably take the deal before he changes his mind. There is a chance you could squeeze out a bit more but I don't know if I would chance it.
I was thinking instead of doing a straight up trade maybe you could do that 1 for 1 but also acquire another player or two from him as well and upgrade your overall team with getting rid of some of your weaker links.
Think you could use a closer upgrade as well as maybe one more decent SP.