Great question — answering as the UphillTech team:
No, center of gravity is not a issue between a tall and short person. That is because the rest of the body scales too. The center of gravity relative to the body height stays the same. Imagine a stool. If you make the legs longer but keep the same footprint, then it would be easier to topple. However, if you enlarged the footprint the same amount as the height, then it would not be easier to topple. It's not just the height of the center of gravity that matters, but that height relative to the footprint or base size. A taller person doesn't just have a higher center of gravity, but also a longer stride, and the ability to extend the feet farther out from the point directly below the center...
Full answer by Olin Lathrop: https://outdoors.stackexchange.com/a/18943 (CC BY-SA 3.0).
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