Thank you for asking and mapping in the CM area! Yes, it is mainly grade 5 from my point of view. But it may depend on the season. It has just rained when I was there and the surface was soft and of soil/sand. During dry season it may be more compact because the surface dries out. How to map this?
I downgraded one trail to grade 4 (https://www.openstreetmap.org/changeset/153975225) but this trail is not smooth at all (like on the wiki-page) and very uneven with runnels. Maybe you remember the situation as you seem to have been there, too.