As much as I'm against 'victim shaming' I have to agree that cycling M roads in KZN is generally a bad idea and the average road safety and driving skill in South Africa certainly doesn't help.
I think it's technically legal and it's not considered highway (I'm open to correction here). We have sympathy for cyclists in that part of KZN, as cycling M roads there is much different to inland. Coastal M roads are more akin to a Highway than mere major city roads as they carry more traffic, have fewer stops or junctions (thus a higher average speed) and mostly have a hard shoulder with a barrier and these emergency lanes. It's more comparable to Jhb's M1 than Rivonia (M40) as Overdrive also mentioned.
I lived in Pinetown for a while and I risked those roads on occasion but you have to be aware that your life is not in your own hands, even if cyclists do have a right to use the road.
