I, too, really wish the shifter was allowed in Sport mode... especially the TT.
I mean, I kinda get why it was disabled as people were using it as a cheat. But if you think about it, so many people are on different equipment anyway: some use controllers with teh d-pad; some use the controllers with the stick; some use wheels from Logitech; others Fanatech; others Thrustmaster.
All that being said, my rig has a clutch pedal and I cannot shift as quickly with the clutch and stick as fast as the paddles. Plus, with teh clutch you always run the risk of missing a gear or not timing everything perfectly and grinding. So there may be an advantage but there are also disadvantages as well. The user should be able to decide which way to go.
Anyway, I digress.