I don’t think the Segway design will work and could only be made to work with with extensive modifications to the stabilization logic. Let’s say for argument’s sake we build a hot rod Segway with sufficient power. When you perform a inside loop, with your hot wheels car or your Extra 300S aerobatic plane you will feel positive G all through the maneuver. That is to say a glass of water in the cupholder will not spill even though an outsider observer sees it as upside down at the top of the loop. I’ve seen such a film takenin the cabin of Bob Hoover’s Shrike Aero Commander during loops and barrel rolls, pretty interesting.
Problem is the Segway is stabilized with gyros which don’t work like a pendulum system. As you go through the looping track the gyro will maintain the same “up” as the outside oberver, not the “up” you feel from the centrifgual force of the loop. Our intrepid test pilot is going to do a rather unpleasant face plant.
If you had a system that allowd the Segway to know what the slope of the ground was and programmed it to follow that you might make it.