The pistons on my Hayes get really sticky really fast, if you can be bothered cleaning and greasing them with DOT grease they feel and sound great for about three rides, then you need to repeat.
Also, the stock pads take AGES to bed in, and until they do they scream like banshees.
Am almost at the end of my tether with mine, far too much faff, and don't get me started on how quickly and how noisily the rotors seem to bend…
(oh, and in general I never pull the levers when the bike is upside down, it can introduce air into the hoses really easily)