The fact is laws of physics cannot be changed, and when you blow hot air into water it will cool it down no matter what brand of tub it is. Now Bain Ultra was the original air tub, their service is top notch, their parts and materials are top notch, and their design has only the bather in mind. Kohler is not a bad alternative, but all things being equal Bain Ultra all the way. Hope this helps.

did you ever get this tub? anyone have it? is it any good?

Moral of the story here is everyone has different wants. Back in the 2000's all I would see are jetted drop-in tubs, so I perceived those to be "the best that rich people bought" lol. Gotta take a step back and figure out your personal wants and how you'll realistically use I agree for mobility, drop-in is much easier to use Heat retention, I'm still voting for cast iron. I've owned insulated fiberglass with jets, used just about everything in between, then own a freestanding cast iron now. Realistically, you draw a bath then sit in it for maybe half an hour. I've seen fiberglass/acrylic units with heat pads in them (...why?) to combat this, or you do what everyone has done for hundreds of years and turn the hot valve on low. My last fiberglass tub, the tub would feel a hair colder than the water as it cooled down at the end. My current iron tub doesn't do that, seems to maintain temp longer, but again metal=conduction. Could think resale, or maybe you'll barely ever use it so it's more for looks. Can't go wrong if you do the right thing for you

Look at the Kohler Underscore with heated bubble massage. It comes in many sizes and has excellent reviews if you search in these forums. I sat in one in the showroom and the lumbar is fantastic. My bathtub consultant said she got to try the bubble massage at a hotel in Miami and said it was awesome. Much quieter than standard air jets, and they have a newer purge/clean function that keeps it from getting mold or gunk to scrub out (like the older jacuzzi tubs). I would buy one of these in an instant if they had a side drain which is required for our build. So we’re having to go with an unknown MTI tub.