Single or variable speed air handler

I'm having a Bosch 2.5 heat pump installed. I've read on here both ways on an air handler. I know the single speed will be cheaper but will it hurt the performance. I'm in Va. house is very well insulated. Also does the air handler need to be a 2.5 ton unit.

source https://hvac-talk.com/vbb/showthread.php?2223664-Single-or-variable-speed-air-handler&goto=newpost