I currently have a T-Mobile 3g phone (Dash 3g) with an unlimited domestic data plan. Planning to visit Canada, I was thinking of putting my SIM in my old unlocked Razr to avoid the dreaded international data roaming charges, but keep my Dash available for Wi-Fi. I wanted to still have a phone available for voice and sms, knowing full well of the charges incurred for them. I just want to avoid data roaming.

To those that have successfully done something similar, would using my non-3g phone be a reasonable workaround?