I think no. By the way, I have seen several pics of Mustangs with the Eibach Pro-Kit springs, and don't like how they end up looking. For some reason (maybe because they actually do) it looks like the springs actually drop the back end more than the front, giving the car an awkward appearance.
I'm sure you could if you absolutely had to for some reason, but no you're not going to want to.. and I've got the pro-kit on my stang and think it looks perfect the back really doesn't sag.. but I got new shocks at the same time if that changes things
i think the only difference is in the rate of stiffness and they have a less aggressive rate on the vert since usually the vert frame is a little weaker and this would accentuate the bumps more...not positive on the other possible differences though