>> As long as it doesn’t leak
On the other hand, eventually, they ALL leak.
We got a gas-fired “demand” heater 3 yrs ago and we love it. However plumbers are not big on them — they are complex (more points of failure) and rely on maintaining good heat transfer with the water (e.g. you have to keep their insides clean, and hard water is a problem). But tell you what — that thing just SIPS propane.
It cost about 80% more than a comparable-quality tank heater though. (~$1200 iirc)
Wait until it breaks.
as a retired plumber I can tell you, I fully recommend fire on demand heaters.