Make sure you do a *22899 on your bb after you upgrade. It will update all of your roaming.
So whats the consensus? Sprint 4.1 or Verizon 4.1?
We havent had any problems with the sprint 4.1 on about 650 devices. Someone did report mail coming in 10 min bursts, but he is the only one of these 650. I think its his device.