We’ve been exploring a thankless solution, but the company that quited us said it isn’t a good idea in our area because the ground freezes in the winter. We don’t live in a super cold area, but it does snow a few times a year and it can get into the single digits of degrees Fahrenheit.
That’s why we installed a tankless unit, it freed up an entire utility closet because we were able to tuck it in to a pretty small space while still respecting the required clearances. The only downside we’ve had was initial cost, and the yearly flushing process, which really isn’t bad if you install the correct valves from the beginning. Takes about 30 min. a year, which is worth it for endless hot water. Our gas bill has also been lower too.