I have never tried riding one where the pegs are even with the axel, so I don't know if it would be any harder. You want to make sure that there is no wobble in the wheel and it doesn't bounce when you start it rolling. Once the wheel is rolling I jog after it, running behind it and determining the speed it is rolling. When you jump and land on the wheel you want your body to be travelling the same speed as the wheel is rolling. When you are mounting and riding the impossible wheel you always want to keep your arms extended from your body for balance.
Quick movements are critical for staying balanced.
Once you are riding it you try to stay on it as long as it keeps rolling. So the faster you can get it rolling when you start, then the longer you can ride it. There are two ways that I have tried to keep it rolling once it starts slowing down. I use ski poles to give me more momentum, just like a cross country skiier. I have been lucky enough to have a very large area to learn and practice the impossible wheel.