Like SLViper, I self installed. One advantage, besides cost savings, is that you get a good understanding of how the lift works, the adjustments etc. There really are not too many bolts or parts to inspect, so there is no reason you can't cover the whole thing in 5 minutes once or twice a year. If you hear an odd noise, stop and look things over with out getting in harm's way. The guy with the failed lift said he tried to move it up and down because it would not lock. He should have stopped and investigated.
When you do the install, many critical parts are already bolted on at the factory (pulleys, hydraulic cylinder, locks, etc), thus reducing the risk of a problem in the field. You will need 2 very strong people or some lifting equipment.