I wouldn't be so sure. I've bought a verizon CDMA blackberry with 3g... unlocked it and popped in a rogers SIM, had no issues other than call display not working properly.
The CDMA side wasn't activated at all...
Hadn't tried it with a Sasktel sim but I assume the results would be the same. As for roaming on Sasktel... it's just possible they don't have a roaming arrangement yet on the 3g side.
Seems to work in firefox