If you plan to stay in racing, you'll soon discover, if you haven't already, that belts are leading the industry. Personally, I've "grown up" with a TC3 but can see how much better the new belt cars are. I can keep up with the belts on a good run but I really have to work the car to squeeze out times and feel as if the car wants to run all over the place. The belts are considerably smoother and easier to drive compared the shafts. Fast is not always the best setup or prep but how comfortable you are with the car.
The FT TC4 is getting a facelift to a brand new platform - that says something. You'll have plenty of room to become fast with a TC4 but I can almost bet that eventually you'll want to go belt. I advise you to skip a step andgo for the XRAY. The car might be budget but has already shown to be as fast as its big brother plus you can always upgrade it to T2 specs down the road.
Have fun