Other than the cool factor, I can't think of much reason to use T rail. Atlas track and MTH scaletrax as far as I know is T, and they come in a lot of different radii and lengths and is more realistic to boot (and Atlas is Nickel-Silver, which doesn't oxidize, though it also won't work with magne traction). Ross and Gargraves are not T shaped, but they look decent and don't cost a ton of money, either, and give you a lot of flexibility.
That old T rail track is scarce and is going to cost you a lot of money. Obviously, if your goal is to run pre war equipment on original track, if you like the 'cool' factor of running on stuff 80 years + old, that is cool, but from an operating or budget perspective doesn't make much sense at all to me.