I have a single. It replaced a first-generation Iron Cobra Roller Glide, which is a slightly updated version of my fave pedal BITD, a Tama Camco.
I have to say, this is the coolest pedal I've ever played! I really appreciate all the adjustability. I have the cam adjustment set for 1:1 ala Roller Glide, and took a couple weeks to dial it in until it felt right.
I definitely have more volume with less effort, and I'm not constantly tweaking it.
Occasionally I tighten the spring to mess around, but I always end up going back to my original settings.
I can play very dynamically, whether heel up or down.