For DPMs, I think some of the main DPM names would be Feldman, Schuberth, Robert Mendicino, Hyer, DiDominico, etc. Those are probably the guys most other DPMs refer to if they find a patient who is a great candidate or wants to be evaluated for possible TAR. In F&A ortho, there are quite a few more US guys who do a reasonably high volume of TARs, and the most experienced in the world are probably a few of the Euro surgeons who the devices are named after.
I doubt I'll put in any TARs during my residency, but I'll likely assist in removing + limb salvaging a few. Even if it is eventually accepted that TARs will be widely used (pretty likely with all the $ the industry is putting into marketing and trials), I think we might see a setup similar to Europe where a small handful of fellowship trained guys (a few dozen "ankle implant surgeons") are doing 95+% of the TARs and getting referrals from their whole state/region for them.
I still don't really know if I'm a huge fan of TARs based on what I read. Most of the studies by the surgeons who designed the TAR or got paid a ton to put them in report outcomes that are favorable and on par with arthrodesis. However, most of the literature that's not funded says the TARs have worse results (occasionally "similar" results) as ankle fusion... even though the ankle fusion population is usually less healthy with more comorbidities and worse ankle pain/function to begin with. With increasing popularity and literature on arthroscopic ankle arthrodesis, that procedure, not TAR, may end up being the standard of care for end stage ankle arthritis with minimal varus/valgus. It's definitely an interesting topic to read about and discuss, though.