Hours are certainly a consideration, but by no means the only criteria. Compact diesels are more than capable of 10,000 hours if maintenance is good and not abused. Sadly most never come close to that. It is not hard to tell if a machine has been abused. Look for a clean unit that demonstates it's owner had pride of ownership.
I look for something that has been kept in a garage and has had regular maintenance. It is pretty easy to look at the unit and make a judgement if the owner used it a lot out of it's design parameters.
I equate 1000 hours to about 40,000 miles on a diesel pickup, really just getting broken in. Would much rather buy a clean well cared for unit with 1500-2000 hours than an abused unit with 300. Two years ago I bought a nice John Deere 790 with 670 hours. Works as new. There were a few things that required attention but after addressing them it has performed flawlessly.
Good luck in your search.