I have just purchased the 50,000 Atwood. It is based off of the PrecisionTemp unit. I have not put it in yet but I also have installed an all brass shower faucet and oxygenics shower head and ultra flexible hose.
I will keep my 6 gallon just in case we have an issue but there are 5 in my family and friends of the kids normally join us on outings as well.
My DW also loves her showers so I will do for her what is needed to keep the peace!!
I am aware that they can use propane but I can't imagine running out in a weeks time.