I had a Rinnai tankless unit installed in our house when we built it in 2016.
Initially, I was going to get an electric heater but the electrical demand is quite high when it first fires up, so I went with propane. At the time propane was relatively inexpensive, and that's what I went with.
The heater is about 40 feet from our master bathroom and it takes a minute or two for the water to get hot enough so I don't suffer any major shrinkage. But, once it gets hot, it stays hot until I'm done with the shower.
We're on rural water and it has a lot of calcium in it. So, I back flush the heater every year or so with white vinegar. In fact, that is recommended preventive maintenance for the heater.
During the winter we will see single digit outdoor temperatures, but I have never checked the incoming water temperature. But it is quite cold. The heater still takes about the same amount of time to get the water hot as it does in the summer.
I wish we had access to natural gas for the heater. There are gas wells all around our house but the neighborhood where we live does not access to gas. What's really frustrating is that there is a gas riser valve about 1000 feet from my house, but that pipeline goes to Memphis.
All that being said, I am quite happy with the performance of the water heater.