Well my obsession with all things arduino and Rpi has led me down the rabbit hole to Raspberry Pints and Kegbot. I got both running last night, kegbot I didn't particularly like the interface so got RPints running. It feels limited compared to Kegbot. I've ordered some cheap flow meters through ebay that are the same as they link to on the adafruit store.
Kegbot you need an arduino board for each two taps whereas RPints you can get away with one arduino for as many taps as you have pins available. Someone also has arduino logging over bluetooth for RPints which could be cool.
Does anyone have experience with both systems, what did you prefer?