I did a lap with the wheel just now and I'm now down to 8.39.693 - 2.1s faster than with the controller.
I'm something of a novice with the wheel, but I know for a fact that I'm very unlikely to go much faster with the controller - the fact that I'm already quicker with the wheel, however, is quite surprising to me.
I really need to study braking points etc. but I'm also struggling to deal with the car on anything less than TCS 2 - I am, however, practicing with TCS 1 on slow corners, and putting it down to 0 on the fly for less tricky parts of the circuit, but even that can distract me to the point of probably being quicker just leaving the damn thing alone