I think Montreal would be out of the question because the government would require that all of the signs were in predominantly French, would probably require that the session notes were available in French first and may even require that the sessions are given in French or at least that they are offered in both French and English. I don't see MS or Advisor going to this trouble for a very small percentage of the attendees and I don't think the attendees and vendors would appreciate having the additional costs passed on to them.
Toni and I were once denied entry into Canada to teach a class. Apparently the rule was that we had to be contracted by a Canadian company in order to come to Canada to teach a class. It didn't matter that 90% of the students were coming from the US and staying in Canadian hotels and eating in Canadian restaurants for a week either. The only way we eventually got in was by contacting Bernard Wong at Microsoft Canada and getting him to say Microsoft had contracted us to do the class. We had to answer all kinds of questions about whether or not there were Canadians qualified to teach the class and things like that as well. This was post-NAFTA too.
At any rate, FoxTeach has always been a better conference than any of the Advisor/Microsoft DevCons. Maybe the thing to do is approach Val about having FoxTeach at an alternate or additional Canadian location. I think he'd be a lot more receptive to the idea than MS/Advisor and it'd be a lot easier for him to set up since he's Canadian and his company is a Canadian company.