I have a 2006 Jeep Cherokee KJ 2.8 with 163K, I bought in 2015, with a full servicing history (poor bastard must have spent a fortune).
Cons
It has been reliable most of the time, but did almost leave me stranded due to a faulty / broken alternator pulley (common issue). Currently also struggling with air in the fuel system (another common issue). Timing belt service is crucial at the 100,000Km. Parts can be expensive, so you have to be smart / resourceful. Not too many people know about these engines, so might be harder to get good service. Dealerships are useless here in Brisbane.
Pros
However they can be fantastic little Jeeps with a few modifications / fixes (EGR delete and Provent a must).
Low end torque is fantastic and addictive (will be hard to drive a petrol once you are used to a Diesel). Fuel efficiency is better compared to petrol (I've done 820Km on a full tank). The Diesel version will also come with the 5 Speed Auto (545RFE) and a better 4WD system (selec-trac offers Full Time).
Haven't had any major high cost work yet (transmission, fuel injection, turbo etc..)
http://www.lostjeeps.com/forum/phpBB...&view=previous
The fuel efficiency of the Diesel will make up in the extra servicing costs (Synthetic oil, diesel filter), so keep that in mind.
Make sure you do a lot of research of what the common issues / mods are so you don't end up buying a project you won't be able to afford in the long run.
Hope this helps.