You simply wouldn't get to Cape Town from Johannesburg - there aren't enough fast charging stations around. Read this real world report on the same car and actual charge rates. Buy the diesel, if you have the money. Now in my Citroen C4 Aircross 1.6 Hdi driving at the speed limit it would sip...
The old Micra was tremendous value for money and very reliable. It was quite cutsie but the new one has gone up a level and seems to be more "car", time will tell if it is has good has the old one.