I have a bike with hydro disc brakes and another with caliper. I'm a lot more "aware" and cautious on fast descents in wet weather with the calipers. Stopping power isn't the issue, it's the precise modulation that hydros provide that elicits confidence using them. There is a different feel from 75" of rim rubbing against pads that are 1" apart per revolution versus the smaller disc with pads 1/4" apart, and any imperfections in the rim caliper setup really amplify.