Toe only. I liked the toe/heel shifters at first, then I went back to toe only. I've got a bum knee from being T-boned in 1977, and it seems to aggravate the knee when I raise my heel to upshift. Just recently took it off, and can't make up my mind if I wanna cap the spline or space and move the toe shift out. Right now I'm leaning toward the cap.
I have been making myself use the heel some but I have to raise my leg to high. I was out looking at my bike tonight and decided to move the heel shifter down one spline. It is close to hitting the floor board when depressed but I will give it a try when the weather breaks.