Not "major" if you're North America based, I took JNB-LUN last year on an SAA 747. The in-flight magazine mentioned there's been a bit of a FF stink over their decision to run a 747 on the JNB-LOS run as well.
Interestingly, the JNB-LUN 747 is a white-washed plane. One of my fellow pax in J said that it had been stripped of its SAA colours when the big push for *A Airbuses started and towed out to the desert (Botswana maybe?), but was rescued and put back into service (without its colours) when SAA expanded their Angola offerings. That said, I have no idea if there's any truth to that.