Let me add a quick correction first, it's the 'race' in Montreal, and the 'big race' at Alcan
I won't go into non-racing details since you have to decide for yourself if you are making this into a vacation and debate the merits of each city separately. Further, I know you guys have raced at Alcan so you know about this festival. I last raced there in 2002/3 so my memories have faded about Montreal but this is what I recall (IMO):
1. Cool to race at the Olympic basin where you have lane markers the entire length of the course. Also no debate about tidal advantage and I would assume you could not wake ride with the lane markers there (what do I know, I don't steer).
2. Starts are equitable since they are held (if I recall).
3. Nice to see your team name and times posted on the big scoreboard.
4. Quality teams from Toronto and Montreal, as well as from Eastern US.
5. Smoked meat sandwiches (OK, this is not race related but you can't discount smoked meat!)
6. The have stands to watch the races right at the finish.
I don't know if they have tents set up for teams (like Alcan) or whether you are on your own (someone else can answer?). Festival ran smooth if I recall with no major hiccups, but maybe someone with a more recent experience can add to this?
To answer your question though, for 2011 I would do Alcan because it's the 25th anniversay. Then I would go to Montreal in 2012 because as something new.