I was really surprised when I saw it included as one of the questions. Obviously real tables behave differently depending on table tilt, state of the playfield, rubbers, etc but I find TPA to be pretty spot on bounce wise.
The bounce, or lack there of, in Zen (FX2) is laughable.
The problem is the ball seems to lack weight. Perhaps that's a better way of phrasing it. It accelerates too easily and maybe is a bit too fast overall, and it makes certain techniques like the flip trap almost impossible. The only real table Zen's physics would work well with is if you were recreating Hercules (which used a Cue Ball in place of a standard pinball). Seems like a Goldilocks and the Three Bears situation: the current TPA build has too light a ball, Zen's is too heavy, so they should try to find a build that is just right.