JNB-Kruger is a good road, generally fast except for a bit through the hills 50 miles (?) before Nielspruit. We do worry a bit about personal safety in South Africa - the odd bit of bad luck could put you in touch with someone who wants your property badly, with limited options on your part. Wouldn't dream of setting foot in Zim these days, but don't take that as advice - haven't been there for at least 10 years.