M5s, each with a single HP driver, sound better than M80v2 which of course have two standard drivers each. That's not just my opinion. It's also the opinion of four others who heard my system.
For what it's worth, I had a similar experience with M5HP's vs M60v4's... although I would probably be even happier with the M5's sound if I could trade the bass bump for a bit less bass.
That said, there's a good chance the difference is at least as much cabinet & crossover (or even the room) as the HP bass driver but I don't know (yet).
