When I test rode one with the forward foot controls, I also found that my feet were tending to slide off the pegs.
At the time, my thoughts were that I would probably need to tilt the angle of the pegs upward slightly, to counteract the sliding.
I decided to go for the mid mount controls in the end, so I never looked in any detail regarding the issue, but I wonder if anyone else has tilted the pegs slightly upward (?)