Starchoice (Now Shaw Direct) will work fine. We use it all the way to southern Mexico. Note that the new (3rd) satellite won't work south of the Canada/US border, the footprint is not wide enough. The original 2 work just fine. If you have the dish with 2 LNBs there will be no problem. If you get the chance, the 75CM dish is better for the HD channels or if you go south into Mexico.
We have called from Mexico several times and have had no issues nor extra charges. I hope that Shaw realises that if they try to charge extra or disallow the snowbirds they will loose thousands of customers.
We'll have to see what happens this year.