I can now confirm for anyone who is interested that the outbound JNB-MRU is a two course breakfast, followed by a bar service and a snack before arrival. The food was much better than CE, drinks ok but fewer choices.

I'm told the return (1600 departure) is a hot meal service too with a snack again should you need it.

The MRU flights are on a 737-800 and I can thoroughly recommend 2A/C as there is an enormous amount of legroom. They are emergency exits though and cannot be assigned to children.