I am still trying to decide between 2 heat pumps, the Aquacal 145 SQ and the Pentair Ultratemp 120Q. My question is this: at 50 degrees, the Pentair had a BTU rating of 82,000, and a COP of 4.0. The aquacal at same temp is 75,000, with a COP of 4.2. Will the lower BTUs of the Aquacal be made up by the higher COP, or will the Pentair still heat water faster? Or would it be so close it doesnt really matter? Thanks in advance!