I do keep weighing up the options, comparing the tax hit to potential growth, but I don't have an answer just yet. It's highly likely I'll spend 6 months and a day outside of SA in the next few years, so that would be the ideal time to do it.
In the meantime, I keep taking out as much as I can with the R30k exemption. This year it works out to about R80k, but using the 4% rule and the decreasing amount I can withdraw in the R30k exemption, it means I'm never able to get the money out! First world problems...