I personally would go with the 82's. I like to keep things simple though. Using a sub however would allow you more control over your sound and be beneficial if you listen to a lot of music with extreme low end. The downside of a sub is having to work with it to get it to sound right in your room and blend with your mains.

In one system I use Klipsch Heresy and I will tell you the sub will need some power to keep up with the Klipsch because they are so efficient. If the sub don't have ample power the Klipsch will drown it out. It takes big power to reproduce bass and even more to produce it loud enough to keep up with Klipsch. The Klipsch subs I've heard have been good and I would imagine they design them to keep up with their own speakers but only speculation.