We have a SEER 15 heat pump that was just installed four years ago. When this one goes, we go geothermal. Even if electricity is only $0.0637 a KwH which equates to about $2.59 a gallon for the same heat as a gallon of $4.00 to $5.00 oil, we supplement with wood in the winter. Nothing warmer than a toasty Vermont Castings stove on a cold winter morning.
I work at Ft Knox and the Army there has gone geothermal to the max. I have given up on counting the number of wells that are being drilled on post on any one day. Each building that is undergoing renovation for the move of the Human Resources Command to here is getting geothermal as are all existing buildings.