I do it dry. lighty press on the pot to loosen its grip. if it is has a lot of root circling, then I use a razor and make a few vertical cuts down the rootball. put in new pot/soil, water.
I have had excellent results when transplanting this way, dont seem to see any transplant shock at all. if I dont score the roots, it seems to be a few days or a week for it to "recover"
Also, if you look up a user "riddleem3" (i think is it) he has a "make it rain" thread, and in there somewhere he describes flooding out the roots, it will make the plant "go to sleep", then do your transplant. I havent tried it yet, as wet soil, falls all apart and trashed my roots last time i tried.