I had a tank less water heater in Europe during the Mid 50's. It was in my home, almost every home had them, they consider water tanks as being ridiculous. I never had any problem with mine. It always worked just fine, you could take one shower right after the other and never run out of hot water. I at first worried about the open gas flame in the water coils, but soon realized we do the same thing with gas water heaters here. Now in an RV with all the shaking and twisting going on I am not sure I would feel that comfortable with them.