Instead of selecting the system I wanted, I selected the company I wanted to use. They came in, checked our needs, assessed the airflow and square footage of our house, and then they made the recommendations for the system to buy. We wound up with the Daikin heat pump in the attic with ducting into the upstairs bedrooms and bathrooms, and then two split-mini units in the common areas (living room upstairs and rec room downstairs) to allow us specific zone controls across the bedrooms and living areas. Heat pumps are not often used in extreme climates, simply because they use the ambient air temperature, and add to or subtract from it. There are various (unsourced) claims that heat pumps are only good for a 40-degree change from the ambient temp. So if it is -20 outside, the heat pump is only going to get you up to 20 degrees inside. Or if it 120 outside, it's only going to get you down to 80 indoors. This is why I'd find a reputable local HVAC contractor and have them suggest the right solution for your location, home, and needs. There are a lot of variables that you can spend a long time learning... or just work with a pro who already knows this shit, and knows what works and what doesn't in your area. (And who has a good reputation for long-term service.)
...and they might have old stock from a mis-order sitting in the warehouse that they can make fit. We have been told by a number of HVAC companies that the furnace we have is twice the size we need, and that we paid basically salvage prices for it. On the plus side? It fuckin' moves some air. On the minus side? I know I need to change the filter when it stops oilcanning the plenum. whump WHUMP