Hi, Montrealer here...
Do as they say and ski in Jay Peak. That's what I do. Tremblant is over-rated, over-priced and worst of all, they send out their army of Snow Cats the minute that a new snowflake hits the ground.
Mind, you that's just my opinion as a hater of lineups and groomers.
On the other hand, it could be a nice place to spend your vacation with the family since everything is in the same area: Over-priced gift shops, mediocre restaurants, lame discos. If that's the kind of stuff you like, then go for it!
My advise would be to take a few days in Montreal for some shopping (be sure not to miss Simon's on Ste-Catherine st.) and sightseeing, then go for a few days to Jay Peak or better yet Head down to Sugarbush, VT or Killington.
Oh, one last suggestion. There's always Mt Sutton (about 1.5 hrs from montreal) which offers some great tree skiing. Lift lines can be brutal, though.