Viezu does an excellent job talking in detail why and when you should tune your car's gearbox and the benefits of the TCU software upgrade. These guys are on top of their game when it comes to the Jaguar F-Type sports car.

 

I had my gearbox tuned when I had the engine remapped. Surprisingly, in the 2lt the gearbox is the 8HP75 which has bags of room for handling more power. The engine map took the car from 300 to 342bhp and 387lbft from 330lbft. The gearbox map quickened shifts and allowed more torque on the lower gears. Throttle response was also improved and pretty well everything described above.
I would definitely recommend one or both.

Rob