Just over six years ago (May 25, 2003) we installed a Bosch tankless water heater. I blogged about it back then and since then I’ve had occasional email with people considering doing the same thing.
We’re still satisfied with the water heater and it still works fine. It’s still annoying to have to wait 60 seconds until the hot water comes on, but the shower pressure is OK and there’s always hot water available.
No particular cost savings that we are aware of, though.