From what I understand, the QC2 had better acoustics and almost no noticable hiss (ANR "artifacts") compared to the original QCs. The latter point makes the QC2 more suitable for wearing for noise reduction only (not listening to music) in airplanes as well as for office environments.

If the old ones are still working, and you don't have someone to give them to or sell them to, I might wait a little longer. The QC2s have been out for about two years now, so I would not be surprised if Bose came out with a new model this fall. When the QC2s came out, Bose reduced the price of the QC1s.

That said, from what I have read, it will be hard for Bose to improve on the QC2s, but in the consumer electronics industry "newness" matters.