I work with HVAC guys weekly on projects, what I have found is a majority consensus among Heating and Cooling people regarding tankless is that "tankless heaters are not as reliable as tank heater hot water systems", this is what they all say.
However, I don't hear about them being called out all the time to repair them either. I think it's a few factors, i)it's relatively new in the HVAC industry ii) most Tech's have little to no experience with them, so they are a little scared to recommend them.
I do know there are limited people that are qualified to repair them so that could get expensive.
Moreover, unless you want to do two 120 gallon commercial grade hot water tanks (for infinite hot water) then a tankless would be a great idea.
I do know in the late winter I will be installing a tankless in my fishroom for the very same reason (infinite hot water!!)
😀
When I do I will let everyone know how it goes.