i have a 5-head alco/selmix refrigerated system set up with diet coke, generic lemon-lime and tonic water. maintenance involves cleaning the dispensing nozzles every other day (soak in warm water overnight), wiping down the machine and drip tray daily, and changing the water filters on the inlet to the carbonator about every 6 months. i buy the smallest bibs i can find, usually 2.5 gallon (the syrup has a shelf life of 6 months usually...)
i like it, it's nice not dealing with cans or bottles, and the drinks are always perfect. my dispenser is a bit of a power hog however... if i do it again i'll build a postmix system into a chest freezer and use a glycol bath to chill the soda and syrup lines.
ice-cooled dispensers use little power and are quiet, but you need a decent-sized ice machine to keep the bin full.