My neighbor (family of 4) has one and he loves it...
Took a little bit of work to modify the existing water and gas lines to do the install...but if you’re handy it’s not above the average do it yourselfer...
http://www.apartmenttherapy.com/pros-and-cons-of-a-tankless-water-heater-176538
I may have to consider going tankless as mine is going on 5-6 years old and it was an emergency replacement...during the winter of course.
Can’t DIY here, must have the proper licenses and permits to install..............
I was in Home Depot one time and asked an employee where the ‘Hot water heaters’ were.
He said, “We don’t sell hot water heaters.”
I said, “You don’t????”
He said, “No sir, we only sell cold water heaters.”.............