I've seen too many of them unload pretty badly, where a front end roll could have easily occurred. Infact, some of the TJ guys are swapping in rear leaves to prevent this.
I'd like to know what anti-squat numbers they were running to see what effect it had on it.
I think with a properly designed 4 link system, you could run coils in the rear, however, to correctly link a 4 link in an XJ, some of your links will be placed inside the cab. Be prepared to hack your floorboards pretty bad.
For simplicity, I'd get some quality leaves, use up to a 1.5" block, some longer shackles, and an anti-wrap bar.