We're getting ready to purchase a heat pump and can't decide on a brand. Pool is basically 20x40 with a small spa connected, 25,000gal total. We live in the Florida panhandle, pool is on the north side of the house with an enclosure. I think I would get the biggest available and, from what I can find, the ranges are from 130,000BTU to 143,000BTU with a COP of 5.5 to 6.5 depending on the brand. The closest pool store is pushing the Nirvana E140 (140,000BTU/6.3COP) at about $4800 but is that much better than a Hayward HP21404T (140,000BTU/6.0COP) for $3500 or should I be looking at the AquaCal SQ175 (143,000BTU/6.5COP) for $5000? How much of a difference is this 10,000 or 3,000BTUs and how much of a difference is a COP of 5.5 vs 6.5 or even 6.0 vs 6.5? Am I missing something or should I be considering something else?