A Bambi IS quiet, but EXPENSIVE, and in our experience, not totally reliable. Our church has one to open the door from the carpark. The reservoir is mall, so it did not run for long periods to charge the reservoir. The first one seized, and the replacement was circa £800. Now running part time, on a timeswitch; a few months ago it ceased operating the door; instead, it just rattled.
Examination showed that a long 1/4 UNF bolt, holding a welsh washer in place, had broken off, flush with the bottom of the as cast bore in which it sat. The bolt was 12.9 grade and ruined two hardened drills, before we managed to extract the remains. After making up a bush, to centralise it in the bore, the hole was gradually enlarged to tapping size for 1/2 x 40 tpi M E. A stud with a 1/2 x 40 ME male thread at one end, and a 1/4 UNF female at the other was Loctited into place, all sealing surfaces coated with Hylomar, and reassembled. So far, it has performed as required.
So if you have, or are offered, a failed Bambi, this may be a means of revitalising it for a quiet compressor.
Howard