I am using a inverter type mini split heat pump today in the Albany NY area, at 0 degrees F. It does not work well at this temp, but is functioning. The output BTU's and the air temp leaving the unit are not high. Consider that this is a great solution to about 20 degrees F. It also seems to be very efficient even at these lower temps. Far ahead of resistive heating, perhaps at least 2:1 at the very worst. The air leaving the inside unit is not very warm, reaching 75-83 max or so at an outside temp of 5 degrees. The operating data is part of the manufacturers specifications, and some units have good test data showing the low temp operation expectations. You have selected a quality unit, mine is a no-name, so you should expect more reliable results. In a high humidity area, the outside unit will ice up, requiring a defrost cycle, some times frequently, every 20 minutes, depending on conditions. This will result in no heat for the cycle and possibly shorter life span and a bit higher costs. Consider the winter humidity ranges before installing these as primary heat in the winter. Also assume that you will get half the BTU rating at the worst outside temp and make sure that you have some form of backup heat. You don't want to oversize the units as that effects the summer operation and the efficiency and installed cost.