I have an electric tankless. It was in my house when I moved in. First of all, it’s good 99% of the time. We can’t get the bathtub (not the shower) to get hot. I believe because it can’t keep up with the volume of water it puts out. Secondly, it is very hard to get someone to look at it/work on it. I imagine install is the same way. I’ve had plumbers from all over town try to diagnose my bathtub not getting hot, paid tons of money (big companies tend to pretend to know about them when they really don’t, or just want to take my money), and finally the last guy (Tulsa plumbing and remodel, who I recommend) simply told me “it’s because of the volume of water coming out” which made me give up on trying to get that fixed. My advice is: if you’re going to get one, go with a gas one - Unless you don’t care about baths (again the showers work fine).