Not had any problems with diffs on ours.
We have had a gearbox problems. It developed a ver minor leak when we first had it, and I reckon it lost so much oil, it caused some damage. The gerabox is one of those sealed for life jobbies and apparently a o ring seal where the electrical sensors plug in hadn't been assembled correctly.
Basically, we've had 3 breakdowns in 2 years which isn't good, but the Jeep warranty and breakdown support has been excellent. We've now had the gearbox, ecu and gear level assembly all changed and these parts carry a 2 year warranty. The breakdowns occured as the gearbox went into safe mode, which means no drive...very handy.
Other than that the car has been fault free, not even a rattle. I'm putting the gearbox down to a one off.
The new Jeeps have far superior auto gearboxes, much smoother change, and the 3.0 V6 diesel is superb. Feels more like a V8.