Spot on. Just don't go full suspension if it's going to see road duty.

My primary mountain bike, an upgraded 2003 GT Zaskar, is also my Jack of All Trades travel bike. With the race wheels and slicks, it's almost as fast as an entry level road bike at 22 lbs. With the sturdier wheels and big knobbies, I can ride just about any trail. It can't do big drops, requires pretty good technical skills, and there are a few trails, like the Portal Trail in Moab, that it's not up to but it gets the job done. I'm not about to kid myself and try maintaining a Cat. 4 race pace on it either.