Well, I use the ERSA SMT unit 60A which includes a desoldering tool. Works a treat! During the development of one of my products I had a big problem with a CPLD that kept 'dying'. I managed to replace it several times before finally some of the pads gave up.

Using a heat gun does give good results as well, but I also have never tested the ICs that come off. Then again: I knew for a fact that they were dead...

Regards,
Rob.