I like JP magazine it has some good articles, but its kinda like reading the internet. Some of the info is good, and some is full of crap. I would take everything they say with a grain of salt. Its just one person's side of the story. Sure they have done some research to back it up, but they are completely WRONG when they say all '97's are bad. Thats impossible to prove. Also with the '99 head issue. The went far enough to single out '99s in the bad category, but missed out on the part that only SOME of them have the coil ignition. Thats pretty misleading if you ask me, and could be giving potential XJ buyers wrong information. I don't see any problems with the RENIX cherokees at all. Sure they might be a little different to work on, and have different systems, but that doesn't mean you should avoid them at all costs.
I grew up with the '87 my dad had, first year for the 4.0L. He drove that jeep for 16 years only needing to fix some oil leaks, a radiator, waterpump, and some hoses. Thats after 180K miles. I used to own a '90 limited and it gave me absolutely no trouble. My 2000 wasn't maintained very well and has some issues, but its still reliable. The '00-'01 head problem I can agree with, that is definitely a manufacturing problem, but it seems between this article and the one on "true power gains for the 4.0L" or whatever it was called, they are turning into a bunch of wackos.