Last winter I used Avid BB5 disc brakes on my trike. They stopped the trike just fine - when they weren't frozen or rusted up.
On a few of the coldest days, the brake lines really did freeze. I would have no braking power at all on one side, and maybe half-power on the other. The problem was from all the water getting in and freezing. Even after filling the housings with WD-40 or lithium grease, and sealing the ends with thick grease, water would still eventually make its way in.
The other problem was the rust buildup inside the brake calipers. Again, it got to the point where I could not apply sufficient pressure to achieve an emergency stop, nor could I adjust the pad spacing by hand - I had to use a torx driver to turn the adjustment wheel! In the spring I was able to clean out most of the rust, but never regained full braking power or the ability to turn the adjustment wheel.
I have been given approval by my wife to get a new set of brakes (apparently she likes the idea of me being able to safely stop), so here is my question: I know that hydraulic disc brakes will work just fine even in the coldest weather (especially if they use DOT oil), but what about rust? Will I run into the same problem as I did with the Avids? What brands would be the best choice?