Interesting.
Just had a discussion with my heat and air guy about these. About a year ago, he put one in his house. I was thinking about it and replaced my water heater instead.
He told me this week that I made the better decision.
Yes, they don't run out of water. When they are running. I don't mean that they mechanically don't run, but when the power goes out a gas water heater still gives you hot water. A tankless water heater used electrical circuits to run.
Electric versions work, but (especially with kids) people get in the shower and stay there. All the while, that little wheel is just spinning around on the electic meter fast enough to act as a buzz saw. Even in the gas versions (which he has) the water usage goes up and so does the gas bill.
Not saying they aren't good, but these are things to consider.
the company he works for now, and worked for a few years ago, no longer will install the electric ones due to the power consumption and the complaints that they got from unhappy customers complaining about their increased electricity bills.
Dave
Haha. My buddy says that the only reason his wife knows to get out of the shower is when the water gets cold.