Grew up with tankless & had one here before replacing with indirect-fired tank.
My opinion? THEY SUCK! Stay away!
I constantly ran out of hot water. Every time I got in the shower, someone would either turn on a faucet to wash their hands or start a load of laundry & the shower would go ice-cold!!
Talk about becoming instantly psychotic!!!
The newer ones are probably much better, but how much hot water can that tiny coil make? If you live by yourself, go for it. If you have more than yourself in the house at any one time, I would steer clear. Just my opinion based on my experience with those....
With the indirect-fired unit, I can do a massive load of laundry, start the dishwasher, have the kitchen sink going full-blast & jump into a nice hot 20 minute shower without missing a beat!