Let me just say this first, and please take this to heart -
If you have to go to any one bar/club/pub in Montreal... GO HERE. You will not only get the best of all three worlds, but you'll have a killer good time!
The atmosphere was bang on. Not sleazy, not up tight, no over-the-top hipster-ey, just an absolute good time! Drinks aren't expensive and there's no cover charge (from what I remember). The staff are friendly. The people that go there are great fun and may I also emphasize that the music is fantastic! You will be dancing the night away with your friends (or anyone, really).
This place is a must.
Just a note - the music level varies from average to very loud (depending on how far away from the dance floor you are)