Tape is not appropriate on compression fittings. The seal is made by the metal-to-metal contact of the ferrule with the socket. Tape can interfere with that. Most plumbers liket to use a little lubrication. I like teflon paste, applied sparingly. Plumbers grease is good, and the most popular is probably a drop of 3 in one oil, on ferrule and threads. All of these reduce shear stress on the metal parts, and make future disassembly easier.
It is quite common to reuse the ferrule. If it tightens up nicely with no feelng that you have to overtorque it, and if it doesn't drip, I see no reason it will not last the life of the valve.
Have you looked at the American Standard Yorkville...floor mount rear discharge? It is pressure assist, but these are a little quiter than they used to be. Should be able to pick one up in the $550 range.