I have regular gain on both sides and IMO, if you need more gain than both sides stacked than you're looking for a distortion pedal not a an OD pedal. With both sides set to fairly high gain and both engaged its (to my ears anyway) about AC/DC level gain. However, I also have a hard time seeing anybody using anything below noon on the gain knob. even if you're using it as a clean boost it sounds better and has more volume with the gain up a little.
I've had a few KOTs and have always had regular gain. I think the pedal is at its best with regular gain. I usually used the red side and had the gain anywhere from noon to 3. I think if you do a search there are plenty of threads on the comparison subject.
When you first start using a KoT it doesn't seem to have much gain but as I played it live , I found myself backing off the gain a bit more and more. It's deceptive because there isn't much compression and we're very used to gain and compression going hand in hand.