“Lol, how long to recoup the initial cost and installation?”
My estimate is 20 to 50 years, depending on usage rate.
And water heaters last about 10-15 years.
I have an iHeat tankless heater. It will supply enough for a shower and sink simultaneously. There are different models.
220 volt line was already there as were in/out water lines....simple installation.
My first propane unit in another home had the electric bill go down $45 per month. Propane was refilled 35-40 gal every six months.
Propane units are even more efficient. Marey heaters out of Puerto Rico have been made for 60+ years now.
I saw no point in paying to keep 40 gallons hot all the time.
The only disadvantage of propane is the unit has to be vented to the outdoors.