Each time my car does for a service, Honda tell me that the rear brake discs are wearing low and should be changed at the next service. Now in my opinion they aren't as bad as the front pads that have a lip on the edge, so I thought I would take them to a local brake specialist.
The guys at Brake Station measure the discs, and compare this against the manufacturers speciafication, both front and rear discs are within 0.5mm of Hondas minimum acceptable width, so Honda were indeed correct.
Brake Stations advice is "The discs are needing changing, but the pads are still only 60% worn, so you might as well take the pads to the metal as the discs are knackered anyway".
New discs and pads all round £340, bargain !