Well, as you may have guessed from my Mosh Pit Training thread I like the heavy stuff. But I only play that when I'm running thru' dojo circuit training (X amount of time on each bag, shadow boxing, resistance band shadowboxing, submission grappling station, ab work, medicine ball plyometrics, and so on), tabata intervals, sparring, etc. NEVER while instructing tho'. I make up cd's (actually using Movie Maker's audio selection) where the music plays during the exercise round, 10 sec warning buzz, end round bell, then 10 sec to get to new station before the music starts for the next round. Makes it real easy to blast thru' a combat fitness workout without having to have an expensive timer.