I took the flight from SH to Mtl 2 weeks ago. only 2 hours in vancouver too. The flight was nearly 1 hour late when arrived in Vancouver, and I spent more than 1 hour on waiting in line of the customs. And I had to wait in another line to transfer the luggage and run a long way to the board. Fortunately the flight to Montreal was delayed 1 hour either, so that I caught my flight...hoho...
However, my experience of first-time landing was much better. Everything was fast. I only spent 1.5 hours on the customs and immigration process.
->Conclusion: it depends on your luck. You could finish all the processes in 2 hours but no ensurance. :p