Anytime talk about single-treadle versus twin-pedals comes up and people have such strong opinions, I feel like I must be a special very dextrous minority, having to operate both Kubota and Deere products interchangeably. I don't really have issues with either. Once you're on the tractor for a few minutes doing serious work, the foot motions sort of fade into the background. If you're not so focused on your work that the controls are still occupying your mind, you're not working the tractor hard enough!! Now if you have some sort of injury or disability, then one or the other setups may indeed be more critical, and that I agree with.
There is a big misconception about how treadles work. You're not rocking the whole thing with your foot. You're either operating the forward peg by the front of foot with heel resting on the floor, or you're operating the rear peg with your heel and have the front of your foot on the floor. At least that's how it's been with my two Kubotas. Very fluid motion. I actually wish my RTV had a treadle, as many times I am in tight spaces and would love to be able to change directions more efficiently.