My Geo went online end of May, and with a the separate HeatSmart meter nicely carving out the HVAC portion of the electric, I have some preliminary cost comparisons from this summer's usage.

For the past few summers, A/C would add around $200-250/mo during the peak 2-3 months of the season.  This summer, the HeatSmart meter is giving me an average of $65/mo for the past three months.

Now, there's a lot that's squishy about the numbers:

• Given the single metering years past, I've had to estimate A/C based on winter vs summer average bills.
• This summer was noticably cooler than most, although the geo did run quite a bit to dehumidify.  Even so, that is probably skewing the costs lower than average. 
  
• On the flip side, the HeatSmart meter includes the hot water tank (previously was propane), which skews the costs higher---unclear by how much.  And as it turns out the valves on the DSH loop were shut off most of the summer by mistake, so I wasn't getting that savings for much of the time.
• The HeatSmart rate is less than the standard rate, but at $65 of usage, the $8/mo meter charge more or less normalizes that. 

But even with the above caveats, that's still a very significant drop.  Will be very interesting to see what transpires over the winter.

I hope the DSH has its own buffer tank to store heat, or else it will be hard for it to help much.

How much dd it cost you to heat water with propane before the switch?

Yes, 40 gal buffer tank precedes the energized 80 gal electric tank.  It's just that the valves in the DSH loop were shut off until late August.

Don't know the breakdown of heat vs hot water on my propane usage unfortunately.