hmm.. berkman > blalock, martin > pierzynski, ludwick > no one.
the things that stand out for me are:
1) you have weiters on the way up, who will scatter his enemies before him (you'll have to move one of him or martin to the bench/ or trade). that being said, stud catchers are always in demand and get primo trade value...
2) you have a nice outfield and ludwick would be a bench player once you plug upton and bradley in
3) you'd have to drop two players to make room for all the extra stuff he's throwing at you. not sure if anyone on your roster is worth that.
i'd stay put for now. if he wants to throw in two more people to make it an even exchange, then you can talk business.