I have put 200,000 miles on my 2005 Libby diesel. On the one hand it is a strong little tractor, and the 26-28 mpg I get from it when not towing is pretty good for a vehicle that weighs 4300 lbs dry weight and has all the aerodynamic advantages of a cinder block. And I know you can tow it 4-down just putting the transfer case in neutral and the transmission in park.
On the other hand, it has been less than reliable.
Do as @ChooChooMan says, and check out the Lost forum. Timing belt every 100,000 miles is not optional, and in fact, if the one you are considering has not had the timing belt done, it should be done anyway due simply to age. It is rubber, and is now 10 years old.
As for it being "no rocket ship," I beg to differ. It certainly isn't as quick as my BMW X5 diesel, which will go 0-60 in less than 7 seconds. But it is no slouch, either. One thing I will caution you about is that it suffers from a serious turbo lag. If you have it in "full-time 4 wheel drive," aka AWD, and you stomp on the go pedal to get away from a traffic light, it will roll listlessly for about 30 feet, then smoke all 4 wheels. This becomes an issue if, for example, you have it in 2 wheel drive and pull out into traffic in front of an oncoming truck. Stomp on the go pedal, nothing happens, nothing happens, nothing happens, then BAM, kick in the seat of the pants as the rears scream and the back end tries to slide around to the side and precede you down the road. I've been driving it long enough to have learned how to gauge the throttle lag and rarely get surprised, but there will be a bit of a learning curve there.
I, too, highly recommend the Green Diesel EcoTune. I put Jeep's heftier Euro torque converter in when mine started to slip. Both the factory thermostat and the mechanical fan clutch are junk, but other than loss of mileage, will not afflict you unless you tow with it.