ZattleBone wrote:

A friend has just come back from South Africa where (as a complete
rafting novice) he was running Grade 5. The kayakers supporting the
raft all went off to do a Grade 6 run in the afternoon. The numbers
seem a bit high to me.

The original poster never followed up, so we don't know which rivers
these were. The Cassady/Dunlap book _World_Whitewater_ describes
only two difficult runs in South Africa:

Orange River (Senqu) gorge below Augrabies Falls, 8 km, class 4+ P
Tugela River, Colenso to Causeway Bridge, 64 km, class 4 P

Perhaps the "P" (for portage) is now being run and is class 5 or 5+.
In my opinion, if kayakers are regularly running a class 6 drop now,
either it was overrated, or has changed to class 5.