I'll pass on Bynum all day long, his pay range vs production doesn't warrant special consideration. He may be the 2nd best center in the league, but he's already making $16.5M and will expect a raise in his next deal after this season.
I think Dunlap could improve him, but I don't think for a second he's a Dunlap type player. Bynum at various times in his career has earned descriptions of lazy, unmotivated, self-centered, immature...all things that would be in direct conflict with Dunlap's core beliefs/expectations. Bringing a project player in (Biz) makes sense on a rookie contract, or with Tyrus (an inherited commitment for Dunlap), inviting a new project (Bynum's attitude) in voluntarily on a Max contract doesn't make sense.