I know there are prevailing opinions about purchasing rental equipment, but I personally haven't experienced anything that would indicate it's any worse for the wear than a machine owner that doesn't know what a grease gun is. If we put the rubber to the road, it matters little where the machine came from and more how it was cared for and serviced.
Check the machine out. Does it fire right off, or does it have to run the battery down from cranking so much to start it. Does it smoke excessively. Very important, pin and bushing connections of joints. Leaks. Pump noises. Condition/color of hyd oil. Tightness of slew ring bearing. Wiring, has it been butchered by some jack wagon with a pocket knife and electrical tape. Condition of cab interior and seat. Does all the switches/functions inside cab work.
I've seen machines with only 1500 hrs that look like they dug a trench through Hades, then find a machine with 6K hrs in excellent condition. Condition of the machine matters more than where it came from, imho.