Just to bring this thought full-circle...the rationale of using thrust reversers at idle power instead of riding the brakes is to save wear and maintenance cost on carbon brakes which can be costly. What about the maintenance cost of the hydraulic actuators on the thrust reversers and other related engine parts? What about the increased risk of foreign object debris ingestion? Correct me if I am wrong, is what's being said here is that the maintenance cost of brakes is still more than the cost of maintaining an engine / thrust reverser assembly?