I've installed numerous recorders on my system, and am very happy I did so. They are used fault recording, long term trending, enrgy audits, power quality monitoring, etc.
It has definetly paid off, I would suggest in the following ways:
a) recording length and magnitude of faults allowed oversensitive equipement to be improved.
b) improving data collection for negotiating deregulated contracts.
c) trending power quality for IEEE 519 compliance.
I'm in a large industrial, and we've used GE Power Quality Monitors, and PML ION meters. Not the quality of utility rigs, but the price is reasonable, and provided sufficient data for my purposes.