We don't live in TV yet but have a Navien NPE-240.
This one is three years old and has never had a problem. The one we had before this was also a Navien but was a prototype. The only problem we ever had with that one was a defective motherboard which the factory immediately sent out a factory rep to diagnose and repair. Since that unit was one of the first of its kind in North America it got special attention. It lasted 7 years. I believe the current model has a 5 year warranty.
I would never go back to a tank type heater. I like the recirc function and I like never running out of hot water.
I do the periodic maintenance my self. Initial cost was a pump,
Robot Check
A set of hoses.
Robot Check
And a five gallon bucket. Now the only cost involved is the 2 gallons of vinegar I use to do the descaling and takes less than an hour. forty five minutes of that is pumping through the vinegar.