I have a 2001 cherokee, and it has 275,000 miles on it so far. I bought it with about 50,000 on it. My evaporator rotted from the inside out about 6 months after I bought it. Moisture, combined with R134a and its lubricant form an acid. If your dealer had the AC opened up for more than a day or so, then the filter/dryer should be replaced. I replaced my evaporator, at the first sign of trouble, flushed the the whole system with mineral spirits, followed by brake clean. Flushed the compressor with fresh oil. Pulled a vacuum for a couple days, recharged, and never had another bit of trouble...that was 9 years ago.
The jeep has been a fantastic vehicle. I don't think the AC systems are too much of a problem.
Dealer quoted me 1200 for an evap replacement, if I had him do what I did, would have been 2K.
The real test will be how long it takes the 134a to leak out that you put in.
You don't want the acids and decomposed alluminum circulating around and through your compressor.
Sniffers are around 150-200 bucks. Too bad you don't live closer...you could use mine