Nearly 3 years and we finally have cold-n-cold running water ON TAP in both the kitchen and bathroom SINKS.
We filled up the big tank with 25 gallons (the minimum) and are leaving it to test the PEX lines and junctions for leaks... so far, so good. We barely have 2.5 psi of water pressure with virtually no head (maybe 6' of fall), but once we add the remaining 175 gallons that will add another 3' of head and get us closer to 4 psi.
I don't care that it's room temperature and won't blast out of the faucet... I don't have to wash my hands with a jug and basin or do dishes in a tub anymore, and that's just FREAKIN' AWESOME!!