The newer (2014) Water heaters are very well insulated now. (+3”) The only stupid requirement is basically anything over 55 gals has to be a heat pump type unit.
The tank-less can be quite problematic especially with mineral issues in the water.
To try to run one on electricity is just insane. 60 Amp supply run to the tank-less.
I see some companies are even putting small tanks for storage on their tank-less heaters. Thus coming full circle again.
I do have high mineral content in my water. It plays havoc on my conventional system, so I can’t imagine the heat exchangers would have fewer issues.
And all I have is electric, not a very viable source for tankless.
There are quite a number of electric tankless or mini-tank systems being sold at Lowe’s, Home Depot and the like, so it’s not as if they’re somehow novel or questionable. Gas is much more common but I know people who have them and are happy with them. As far as mineral deposits, I as well as most people I know on well water have issues in that regard and have whole house water filtration and softening systems, those are not that costly either and come with new construction now. The water is acidic here, not doing so would put pinholes in copper plumbing eventually and wreck the house with water leaks all over the place.