With wheel you can "fast steer" to value that will cause massive understeer (front tires going over the peak). Not sure if it will let you go to the full lock, but it for sure lets you induce that understeer, which you can't do with a pad.
So understeer wise it's ok. That's the least of an issue here.
Oversteer situations are a problem. Now when I drive some cars that I would expect to be harder and can see in telemetry what is really happening with steering, the game stops being fun.. It sucks knowing that the game is driving and not me.
Anyway, look what was pasted by Chromatic9 on gtplanet. I think this is what Danowat was talking about:
No buffers with wheel my ass mr. Dan Greenawalt