Yeah, although in the case of Whitehead, we're a long, long way from above-knee prosthetics being anywhere near as fast as anyone with knee joints, so I don't see that being the driver behind that particular decision.
Interesting article though. One of the commentators for the biathlon said something similar about side-differences, not because of prosthetics, but that skiers using a single pole on the left versus on the right were better able to handle certain turns. At a certain point, even in a sport with factored times, it seems like there has to be a certain amount of inequality just built in.
Markus Rehm's case is interesting, although I feel like it's missing a piece of the puzzle to not mention that virtually all (I think it was something like 8 out of 9 in the last world's) wears exactly the same blade that he does while he's jumping nearly a metre further than them every time. If the blade itself were a straightforward advantage why aren't they all benefiting the same way? As much as I respect paralympic sport, I think Rehm is a lot more fun to watch when he's in grand prix-type events with able-bodied athletes because at least there he has some competition. He wins by such huge margins in para-athletics events that as a viewer you're really only watching to see if he breaks his own world record.