Simon, the T handles are great for jigging, particularly on overhead reels. If you are thinking for popping....forget it, they are a pain in the a#$e on the cast and really unwieldy for popping.
If you are thinking for jigging, with a spin reel, just be mindful of the butt length of the rod you use, they suit rods with longer butts better than a short butt rod, where you might find the handle interferes with your 'love handles' (belly) when you jig under the arm. They can also add quite a bit of leverage to the whole spin setup if used incorrectly (think broken handles).
Jigging Master do some great T-handles.