I have the TimTam and so does my colleague. Couldn't pass up the 40% military/vet discount, made it $240.
Theragun is horrible if you're in a clinic setting. It is LOUD! It does have nice little features, but nothing that justifies the $600 price tag. I've used it side-by-side with my timtam and the theragun does hit a bit harder, but not by much.
the hypervolt is... $400, I think, looks nice, I hear good things about it from colleagues.
I see constantly other chiropractors selling their theraguns to buy a timtam or a hypervolt. More so a hypervolt because of the look and features.