heatpumpfan

Are you able to say more about that? "We will have local contractors" sounds great but in my area I don't think you will be able to find anyone to work with you. The local contractors and supply houses have closed ranks to fend off internet sales. I can't even buy sheet metal from the local supply houses without presenting an HVAC license. These folks are seeing their livelihoods threatened by a looming shift toward the "appliance" model (which I for one surely welcome) so they would see partnering to service a model like this as slitting their own throats.

You have an older system. New systems can provide 100% rated capacity well below freezing. Mine is -5F and not specifically a "cold climate" unit. The unit in OP seems to offer 100% nameplate capacity at 5F.

>"backup heating strips"

Big resistive elements sitting in the air handler. Think big toaster oven coils that are used when the outdoor temperature drops too low for the heat pump to handle the load.

I recently purchased and installed a 3 ton MrCool Universal (Gree Flexx, I believe) with lineset for ~$4K shipped: https://hvacdirect.com/mrcool-universal-36-000-btu-heat-pump... Worked just fine during the Christmas arctic blast. We will see about longevity but at 1/3 of the price of your proposed units, I'm not worried about slapping a new one at any time. I am essentially on my own for service as no contractors will work on it but it seems your units would present the same problem.