Maybe not a good comparison, but Mom & Dad had one in their house...or I shouldn't say "one" but rather three over the course of 10 years. Not sure of the brand(s) but they were installed by a local plumber, not from a box store. They just didn't seem to last compared to tank models, and had to be replaced due to developing leaks (rusted out) on fairly soft rural water. Surely some must have a better anti-corrosion system.