I have had a Bain Ultra for ten years or so.

-Works fine
-Yep, the blower is noisy. Mine is in a knee wall space and surrounded with insulation, which helps, but it's still noisy. Connects via regular ABS or PVC so you can put the blower where ever it is practical for you.
-There is an electric resistance heater in the blower, so it actually blows hot air into the water, but this merely slows the cooling of the water; it does not pack enough BTUs to maintain the water temp. To keep the bath warm you will have to add hot water periodically.
-If you have a smaller hot water heater, (I have a 50-gallon), set your water temp high and use tempering valves as needed, to ensure you have enough hot water to fill this beast.
-Purge cycle can be annoying, cannot be disabled except by turning off the power, and you have to make sure users know how it works. It's not a good idea to disable it anyway since the jet airways would then fill up with dead skin flakes, soap, dirt, body oil, bubble bath, spilled wine, etc. that would stagnate until the next use. Yum.
-I have it set to purge every day at about 12 noon to remove residual water etc.
-It is still necessary to clean the airways with a vinegar solution every so often. Turn on for a minute, let the airways refill with solution for a few minutes, turn on again, let sit for 10-15 minutes, turn on again, let sit, etc.
-After vinegar I fill with clear water and rinse completely.
-Then put in chlorine bleach solution, run a few times briefly, drain and rerinse.
-I have used it exactly once and as soon as I got out, I got in the shower. I am not a bath fan in any sense.
-My wife uses this tub frequently and loves it, except the purge cycle.

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Links to the State of Wisconsin Plumbing Code:
[dsps.wi.gov]
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I am not a plumber.
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