I’m sure they’ve improved since I last checked them out (10 years ago.) I’ll look into it again.
I haven’t retrofitted one into my house yet, but I do have a smaller one with reserve tank in an RV, took some fiddling to get it so it would work well with “navy showers,” turning the shower on and off to conserve not just hot water but water period, a concern when dry camping since you’re limited to the contents of a 50 gallon potable water tank. I’ve been pretty impressed, was dubious at first but cheap and original 10 gal tank system needed replacing anyway.