I have BB7 brakes on two of my bikes and have been using them for a few years now. I like them for simplicity an ease of use and maintenance, but these brakes have not been trouble free. After few winters the pistons on these brakes seized up so bad that it was impossible to turn them and do pad adjustements.
Just today I had to take the calipers off the bike and then disassemble them completely for some serious cleaning. Taking them apart was easy but I was amazed how much crud and corrosion was inside, it took me some time to scrape and clean all the crap out of there and then lube them and get everything moving smoothly again. Assembling them back together was a little bit more awkward because of trying to hold the little spring on the inside under tension while tightening everything back together. These brake calipers are not sealed very well from elements and salt water has a way of getting inside and eventually everything will just seize up and stop moving...I've also had problems with hydro brakes many years ago,, seals would corrode and fluid would start leaking. At least BB7 are easier to work on and no fluid to mess around with. One of the reasons why I love riding my fixed gear bikes in winter is because there is no maintenance and even if brakes stop working I can still stop.