That's a coincidence. Yesterday, I actually asked support (via Contact Us) if brokerage fees were applicable for this action and what they were. This was their reply:
"This option pertains to corporate events. Companies may elect to pay out dividends in cash or in shares. When that happens you have the choice to elect either cash or shares. In most instances, companies would pay out dividends in the form of cash, you can then decide whether you would like to re-invest that in more shares. Should you decide to reinvest the brokerage would be included should there be any."
Which was pretty not useful considering what I had asked... but it's the first time I had contacted them with a problem/question in a year almost and had forgotten how difficult it is to get some useful support here.
So, since brokerage is applied, you might as well just get the cash since your dividends could come to something small like R80 and your brokerage could be R70... You'd be better off buying the shares yourself so you can determine whether or not it's worth it. That's what I think.