I've got GOODMAN 4 Tons, 14 SEER, 15 KW strip R410A refrigerant heatpump with variable speed motor blower air handler I think SZ014 or something like that. The thing comes up like a wild cat slowly increasing its speed. I think it's pretty cool. Not sure about savings yet, but seems to be attractive that it does not explode with sound right away as the regular heatpump with fixed speed motors does. Any experiences with VARIABLE SPEED MOTORS? Please share.