I am also happy with the tankless heater in our Seneca. I dial it in when we first get to a campsite and then leave it alone. The best setting does change depending on both the campground water and outside temps. Once it is set, though, the DW can take as long a shower as she wants without running out of hot water.
I think the biggest problem is that most folks don't read the directions.
Ty & Deb Montag
2015 Jayco Seneca 36FK
2014 Honda CR-V toad