Have thought of this as well and have decided to stay with the tank. I have an instant at home (one that does the whole house) and LOVE the fact that when you turn it on you can run water 24/7 and never run out of hot water, great for a large family that showers one after the other. Hate the fact that when you turn it on it takes a while to fire and you get cool/cold water for a few seconds, not good for applications where you turn water on and off like rinsing dishes with hot water from the tap(my wife does that and gets SO MAD).
We used some instant units at a church youth camp last year and they really impressed me (ran on D cell batteries to fire the flame) but the same issues at home, if you turned off the water to shampoo your hair when you turned it back on you had a burst of cold. Many screams from the girls side when this happened!
