I've got TRP HY/RDs on my commuter, and I agree with woodway that they are a big upgrade over BB7s which were themselves better than any other road mechanical discs I've used. Still the HY/RDs are not nearly as good as the full hydraulic XTs on my mountain bike. I'd say they feel more like the MTN version of the BB7s except that the HY/RDs self adjust for pad wear.

A friend of mine who has used both HY/RDs and Gevenalle full hydraulics (TRP Hylex with Gevenalle's shifters bolted on) says the full hydraulics brake more like full hydraulic MTB brakes.