I have changed ONE person from electric tank to electric tankless. Two older people are the only ones ever there. Probably never use more than 3 GPM. They had to install a separate 100 amp service just to run the heater. (Can't recall brand & details. Sorry.)
They seemed to be happy with it. However, it is a very rare occasion that I think a customer would be happy with it. I would not have even installed this one but it was his design, his dime, and I made sure that he understood perfectly what to expect, he was responsible for the choice, and no callbacks.