I haven't looked up the ex-SA OWE fares (see the spreadsheet), but they sound like xONE3 fares and you would have to buy an xONE4 fare (or higher) for ex-JNB travel (adding roughly USD 1000 to the price). I presume this is a circle fare of some sort, though I have never seen a "circle Atlantic" routing before (kind of hard given no South Atlantic crossings). You'd have to give us the fare basis before we coud comment on what the rules might be and whether it is a good deal, or not. On the surface it is an average deal (neither good nor bad).