Most would advise NOT buying before you try it. However, I have done exactly that (bought on a whim because I generally liked the model I was considering), mostly with success.
I suppose then it comes down to whether or not you can afford the horn AND can then afford to have it put into playing order after you get it. I'm guessing that if you really want a TH&C (and they ARE good conversation starters given their unusual design-look), then take a chance, assuming the price is right. Mine is a good player. I had both the Big B and the TH&C overhauled by the same technician. I like the Big B better than the TH&C, but I'm picky . . . nothing to do with the mechanical design, just the response. But again, that is personal and maybe unique to my TH&C.
By the way, most TH&C's are lacquered brass with silver trim in certain places. Is the one you are considering silver-plated all over? Factory or after-market market? DAVE