So, to clarify, in every case I've read or heard of, when people mention problems with irratation or problems with sensitive skin, it wasn't an issue while wearing the pros-aide, it was an issue of removing the stuff. So "sensitive" doesn't so much mean "sensitive to various chemical compounds" as much as it just means "delicate".
I wouldn't be surprised if some of the removers had stuff that irritated some people's skin. The removers can contain solvents like naptha or potential allergens, like limonene (a component of citrus oil). Personally, I've only ever tried Ben Nye's Bond-Off! and wasn't very impressed with it.
I haven't had a chance to play with it, though I'm starting to think about getting some of both it and the no-tack just for the fun of it. I would venture a guess that it's not going to have quite as strong of a holding power as the original PAX, but in I suspect in most situations, that's still strong enough to hold up during a 1-day cosplay. If it turns out that it degrades in the shower or overnight, and you want to continue the cosplay, then that just means you wash it off completely and reapply it the next morning; no big deal.