Will you take longer showers?
Will you take longer showers if you have a tankless water heater?
I feel that we haven't been taking longer showers. Although you can shower as long as you like, most of us have better things to do. In our house, we seldom ran out of hot water with our tank anyway. On one occasion in August though, we did end up using more hot water because it was available. We had company over and 3 of them took a shower as well as 2 of our household. Because there was no limit to the hot water with the tankless unit, we all had hot showers. If we still had our tank, there would have been at least 1 person who wouldn't have been able to have a hot shower (as the tank would have been exhausted). As such, there will be times where you end up using more water and energy because there is no limit.
One thing to note if you do have teenagers or someone who tends to take too long a shower - you can't seem to adjust the temperature of the unit while it's operating, but you seem to turn it off ;-)