@pc1 1700 on LTE is very important, the majority of the LTE backbone is going to be on that band. 2600mhz is shared with Bell and that has poor building penetration. You're essentially looking for bank 4 coverage. As for 3G you just need 850 and 1900...
I've run into this issue too. Not sure if it's related to the fact that my number was on a VoIP provider or not. When I ported my wife's phone number over, it took a few days for SMS to start working again.
I think the next logical choice is Mexico. Having said that, phone plans are cheap in Mexico so offering roaming plans that don't suck is going to be a tough thing. I'd love to see US roaming at PM complete with Roam Mobility though. Fixed daily plan...
