My disc brakes squeal too when they get some some crud splashed on them. It bugs me but beats pulling a break lever and not even slowing down a little, -which happened a couple times to me in the winter with rim brakes.

I'm glad we're seeing these kinds of posts because I find it reassuring that it's not just my brakes. It will also give potential disc brake owners a heads up as to what to expect from them. For a commuter I'm wondering if a more ideal combination might be a disc in the front and a drum or roller brake in the rear. If you just need to gradually slow down or stop in wet weather, you can use the rear brake without waking up the neighborhood. If you need to stop now, use the front.

I had that kind of set up for awhile the but the grease in the roller rake turned to molasses in cold weather and the bike didn't roll as well. Perhaps a drum brake?