Good BUY Variable Drive..
1) The price for variable drive is $400.00 difference and you don't see the savings..
First thing to remember is there is variable drive not multi speed.Multi-speed has high for air condtioning and low for heat.
Variable Drive adjust to dip switch settings inside the furnace,and most 90% furnaces have (2) stages of fire.
A) Low stage is first called on thermosat and if single stage thermostat, after 10 minute of operation thermostat still calling for heat, unit stops and fires to second stage . As for the blower the variable drive design is very quiet as is ramps up according to settings, so you can watch t.v........
Savings in this area are from 12-17% on 2 stage variable, but this is Texas and we don't get very cold here...
'Life begins with the journey each day'