IMHO, Bynum is not one of our two best players. As you said, he is a project. As for Mihm, he's gonna walk anyway after this year, so we might as well get a great defensive 3(He's not and ideal bench player mind you, and can very well start for the Lakers) in return.
Now Memphis might very well be interested in this deal w/ Lorenzen very likely to walk. A Mihm/Gasol frontcourt would be nice for the Grizz. And they too would have someone who might(!) develop in Bynum. They lose a very good player in Shane, and someone w/ upside in Warrick and their pick, but this I think would benefit both teams.
For the Lakers, we move L.O to the 4, sign(hopefully) Banks for the entire MLE and we would have a very very solid starting lineup.
Now all we have to do is use our LLE wisely, acquire a solid vet for the bench w/ our vet minimum, and make some more trades(trade our picks and some of our 3's) to solidify our bench and we'd be set for the 2007-2008 season.