Montreal is a great choice indeed. I am originally from Europe (Germany, short time in Holland) and have built tech companies on the West Coast (Vancouver, SF). After a decade on the West Coast, I moved to Montreal in 2010. Really enjoyable city with a great mix of high quality of life, culture and massive diversity (which in my opinion - even more so that universities - is the cause of the "intellectual" environment that you seek).
My outfit, TandemLaunch, has built 20+ deep tech companies in Montreal with people from all over the globe (some 40+ countries of origin). Depending on your background, there might be opportunities for you in one of those. Our companies range from early stage to those with 100+ employees so there are opportunities along the entire risk/reward spectrum (see here http://www.tandemlaunch.com/#portfolio). Obviously there are plenty of other great companies in Montreal as well.
Happy to help with any local insights if you are considering this beautiful city (including with immigration since we have literally done this 100+ times).
cheers Helge