Love what you're trying to do. I recently moved most of the way off oil-based hydronic baseboard heating in my 1800's New England farmhouse through installing 3 ductless mini-splits with Mitsubishi Hyper Heat condensors. Just to help with your user research, my biggest decision points:

1. Cold weather operation. I get you're saying the units are good down to -15f, but there's nothing like the fact that I can talk to plenty of other people who have good experiences with Hyperheat at -15f to ensure that they'll actually work. Given I'm using these primarily for heat (the AC is a bonus), if they didn't heat well and efficiently at 0f then it was all pointless. 2. Repairability. Again, given I'm trying to use these as my primary heat, I need to know I'll have someone who will service the unit who can be here in a matter of hours. This is why I went away from the DIY route. Most installers around here (semi-rural New England) are super brand aligned and won't service the stuff they don't install.

Would be happy to help with user research if you're looking for folks to talk to.