It still doesn't make sense that the rears wore down before the fronts. Very atypical, regardless of ESC. I would check your brake bias, it may be off.
How many miles do you have on them?
My brother had a '99 Z28 Camaro which he autocrossed and drove pretty hard. He grew sick of his front EBC pads as well.
At the time I was working at an auto parts store and ordered him a set of Satisfied GranSport Carbon Ceramic pads (GS5). He loved them...said they were quieter, dusted less, bit harder, stopped better, and gave better pedal feel. He also liked that they didn't have to be heated up to perform well.
Unfortunately, Satisfied only makes the GranSport Carbon Ceramic pads for the fronts on the Liberty. I was impressed as a whole with Satisfied and would be willing to give their other lines a try. They do offer their Pro Performance and Pro Ceramic lines for the Liberty rears. The latter of which are supposed to be corrosion-free, provide increased friction, and low dust.
http://www.satisfiedbrakes.com/
Aside from that, I think you are going to have a difficult time finding true performance pads for the rears. Lets face it, we have Jeeps not Porsches.
In all probability, the difference you would feel would barely be noticeable by adding an aggressive pad to the rears. The fronts do most of the braking and are much more substantial for that very reason.
A good deal of the cars I have worked on have had the front pads replaced several times (2-3) before needing the rears done. Like I said before, I would have the brake bias checked.