For me, my BlackBerry (8100) used EDGE anyway, so I'm not losing anything on speed, plus it has WiFi, so it is much faster where I can get a signal.
I had put off buying a new iPod for a long time (my Shuffle doesn't count), since my 15 gig 2G died (some parts are still alive as they were used to help revive a co-worker's iPod).
The only thing I will miss if sync with my Outlook, although if I get a promotion at the end of the year they might give me another BlackBerry anyway (although this time they will pay for it)