As mentioned, there are already 4 bumpstops in the front without this thing, yet only two in the rear.
Since the wheels are outboard of the bumpstops, if jumped, a center bumpstop isn't going to serve any purpose, no? I guess you'd have to measure to see which stop would hit first, the spring or diff.
FWIW, I'm running shortened bumpstops in the front of mine (the ones over the spring perches) as well, so if there was an issue, I would think I would have found it. Of course, I'm not jumping the thing, but even if I was, I don't see how a center bumpstop is going to help with four outers already in place.
Even with axle-wrap/pinion climb this thing would be worthless, the springs are bumpstopped for wrap already, and the amount of climb the center one could control would only come into play with the suspension compressed.
*Perhaps* if the suspension is fully compressed and the pinion climbs, the front shaft could run out of play?