Pentair Whisperflow and other companies have 2 speed pumps that run on 115v so that should not be deciding factor. With the 2 speed, you can get a 3/4 HP full rated pump so that all your features and vacuum will work properly when needed and you can run it on slow speed for extra savings.

My point with the calculation was that with the 1/2 HP, your head loss will drop to about 40 feet (corrected for your actual current BHP). So the 1/2 HP pump would provide about 63 GPM. You need to compare this with your current GPM to see if it is significantly different. My guess is it is slightly less.