I think this is a good place to ask this since geo has the desuperheater options which suppliments or replaces hot water so Im hoping that some of you have experience with tankless water heaters

Im looking at replacing my furnace possibly with geo

If I do this I would like to use a desuperheater to replace the electric water heater it is 80 gallons and a pig using about 25kw electric per day

Or if I use a Air source heat pump would still like to possibly eliminate my electric water heater

The question is I probably wont be able to supply hot water 24/7 with the geo desuperheater
and if I use the air source heat pump no hot water supply at all

Is a tankless really efficient enough to warrant the replacement costs in the real world?
Ive read where it may not be effective enough in northern climates that have cold ground water
Im in Ohio 50* ground water I believe
Thanks
John