For those that don't know, T-stop is another method of measuring the aperture while compensating for light loss. It is commonly used on cinema lenses.
This thread explains it all quite well: http://www.scarletuser.com/showthread.php?t=882
One main benefit of these cinema style lenses is a smooth aperture adjustment and smooth focus adjustment. They typically don't have hard "stops" and can (usually) easily go to a 1/3 or 1/2 stop increments between the markings which makes them able to "pull" focus or aperture during a shot. Among other things, the new Canon cinema prime lenses appear to be much "faster" than the current Zeiss CP series. They seem to be more on par with the RED series of primes, but until they're put into use and tested on the same camera in the same conditions, it will be hard to figure out the real difference.
Old used PL mount lenses still fetch a huge price tag on the used market, so anything more modern will absolutely hold its value for years to come. Wouldn't expect to see any "cheap" Zeiss CP's or Cooke's out there anytime soon, unless either of them come up with a budget line to compete with Canon, RED, and themselves.