They’re not bad, we had them in an off base apartment in Japan. Although there and at the time we aren’t talking “full house” tankless. There were two small units, one in the kitchen and one in the bathroom.
We found them to be very efficient because you were only heating the water you were going to use, not heating and reheating water for storage.
One disadvantage of the full house tankless I’ve heard is that you have to watch multi use activities, such as taking a shower, washing dishes, and washing clothes all at the time time. Unlikely the tankless will be able to supply them all at once. A little lifestyle changes to series instead of parallel events and you(c) are fine.
It will save you a couple of bucks annually on electricity, at best. Meanwhile, the new units will cost hundreds of dollars more, and will negate any “savings” you may have otherwise had.
Whoever thinks the government is doing this anything for “the people’s” best interest is just plain dumb at this point.
