Looks pretty solid. There seem to be 4 separate pumps and feeds that only really merge right at the faucet. There's one such machine out there that only has one pump with a really long shared tube so when you order a drink you basically getting a measure of suprise liquid first (which might be water that has been sitting in there since last use)

I wonder though if you're going into the trouble of adding an elevator, could you make the pouring work on a purely gravity fed basis?