I was watching a few onboards yesterday and the general impression was that drivers like Ogier and Loeb pushed full speed in the not so rough sections but were as slow as anyone else in the rough parts.
It was the ability to immediatelly change pace that made the difference (didn't see much Rovanpera or Katsuta yet).

Breen, Solberg etc had similar speed as them on the rough parts but didn't push in the others.
Fourmaux tried pushing everywhere on Saturday morning and immediatelly broke the car.
Neuville seemed to bounce/smash notably more than Toyotas, not easy to always tell if IT was driver or car+settings bouncing much more