I think I can compete on my DS4 with all but the very best wheel users, the main difference to me is the ability to get the power down out of corners and accuracy of the steering at very high speeds. On the maplewood Evo challenge I could match Kie's line exactly (T500 wheel user and winner of all the Evo challenges I believe) but he would always pull away on corner exit. I think this is down to a combination of throttle sensitivity (lots of pedal travel to adjust amount) and fine tuning steering input.
I would like an icon to appear on the results screen to say whether a wheel has been used or not. I was asked last night by someone about what wheel I use and would recommend so I do think it's the first thing people think of if they can't beat a time (it's certainly the excuse I use!).
If you see their ghost its super easy to see controller users. They twitch steer vs smooth turn. Friend of mine pointed that out so now I laugh every time I see bump bump bump bump around a curve.