Our rig came with the Atwood on demand and we love it. And yes, if you want hotter water you turn the flow rate down. We usually use the flow control on the shower head (oxygenics) for this. Getting used to it is really a non-issue. Even our grandkids have no problem with it and the pressure is never an issue. Just be sure to get an oxygenics type shower head.
We spend about 3/4 of our time dry-camping and I can guarantee you it doesn't use any more water than a tank type. We take 'Navy' showers using the shower head to shut off flow when soaping up.
Given a choice, I will never have another standard water heater with a tank. We are too spoiled now with endless hot water
Scott and Liz - Southern NM
2012 Wildcat Sterling 32RL - w/level up (best option ever)
2007 Chevy 2500HD 4dr short bed Duramax w/allison
Reese Fifth Airborne air ride king pin coupler with Sidewinder