OK - I did one helluvalot of research before I sold all of my worldly possessions and went fulltime boondocking...........
That said 1 of the items I took one long hard look at was 'Hot Water on Demand vs. Hot water Tank and I went with Hot Water on Demand and have no regrets what so ever - wouldn't have a hot water tank again at all. In fact IF i were ever to build a stick house again to live in I would have it there as well.......
Like anything new - there are a few things different from what we've spent years getting accustomed to with a tank system vs tankless but a little familiarization & experience & you'll likely be an advocate as well unless you're the type of person that just doesn't like anything 'new' & different - even if it is an improvement - function , efficiency and cost.
The main things I found out to keep in mind:
the system will essentially warm the water by about 40 to 60 degrees so if the ambient temperature is WARM - 80 degrees say; and the water in your fresh tank is then say 65 degrees or warmer and you have the temperature control set High, the water will be warmed to a temperature exceeding 120 degrees which will caUSE the system to begin cycling cold, hot, cold, hot, to prevent scalding - so you'll need to turn the temp down.
If, say, its 25 to 30 degrees outside, now you may want the temp control set higher........
Also, the system needs a flow pressure of about 45psi; so if your water pump doesn't produce this amount of pressure, the system won't work; BUT If your battery(s) are low on power and can't produce enough amps to operate the water pump fully this can cause the system to not function properly.
And if you are low on propane, you know its going to run out while you're taking the shower.
The brand I have is made by Girard & I'm very satisfied with it.
Also, I boondock fulltime in Michigan till late November and have experienced temperatures into single digits and have never had any issues. I love it.
Jus sayin.............INTJohn