Transitioning from TS3 Driver to TS4?

The TS4 is specifically designed to reduce ball spin from a TS3, resulting in a more piercing ball flight. Depending on how the TS3 "fits" your flight window, the TS4 will definitely be in a different spot. Even if you don't get to a fitting (and should if you are serious), you should at least try a demo and see if the TS4 ball flight fits your eye better. Contrary to something like a M5 replacing the M3 in another vendor's lineup, the TS4 is an extension of the TS line (now -1, -2, -3, and -4), and is not the next version of the TS3.