I run it on a standard 40/40, tds in 350ish, tds out 15. (before I used a booster pump the lowest it would produce from tap pressure was mid 40's).
I have yet to time it for large amounts, but it filled a litre jug in 35 secs. (insert complicated mathematical equation here).
I think it was June at GAPS who recommended it (unofficially) but it seems to do the trick just nicely, mine was off e-bay, new, only about 80 squids plus delivery...