JM You state, "the jury is not stll out". You may not be convinced,
but myself and 99% of others I have read see the savings. As an example
my summer gas bill is 5-6 therm now with cooking all food on gas and 1-2
loads in a gas dryer each week . Yes I transfered from electric tank,
but my electric bill dropped 30$ a month with a 5 yr old Rheem with foam
insulation and fiberglass blanket . The electric was set to its lowest
setting, apx 105f, if it was set 20-30f higher as many do my verified
savings would have been much greater. I save apx 200 a year as I figure
it, at that savings I can afford a repair when it occurs.

Without a tank to rot out in 10-15 years, or build sediment and
reduce efficiency the tankless life of 20-30 years becomes an even more
atractive option . I just pulled out an 18 year old tank at a different
location on Chicago water it had apx 12" -14" of rock hard sediment in
it, that heater was probably running at 50% efficiency, where that won`t
happen on tankless, how much efficiency robbing sediment is in your
tank?