You might want to take a look at the early retirement thread here:
http://shareforum.co.za/shares/when-do-you-have-enough/In my view it doesn't really matter when you can touch the money, as long as it's well invested up to that point. Say you need R15 000 a month to live on, or R180 000 a year. We could fudge some numbers and say you'll need to draw down R200k a year before taxes.
If you want to be reasonably safe you could choose a 4% draw down of all your assets, meaning you'd need R5mil to pull out R200k a year. Now you can imagine that you might have R2mil in an RA and R3mil in a regular account. Technically it doesn't matter how you pull your 4%. If you're only 40 you would have to pull all of it from your regular account. That means you're drawing down 6.7% of that account, and it'll likely eventually be emptied.
But, fortunately, while you've been doing this, your RA has still been growing, so that by the time you hit 55, your total net worth is actually far higher than it was at 40, the only difference is that now you have more money in your RA than in your taxable account.
What you need to figure out is what will the tax saving be in your RA, as unfortunately RAs are designed to under perform the market as they can only be 75% in equities. It's hard to say how much it will under perform by, but if you're in a high tax bracket then probably not enough to make you ignore it. You can try run some numbers on erwintr's spreadsheet here:
http://shareforum.co.za/shares/tfsa-vs-ra-vs-satrix-calculator/Anyway, that's all the theory. In practice, I don't have an RA. For some rather complicated reasons, the RA wouldn't reduce my tax burden, so I am an exception. That said, I really do like the fact that I can manage my own money. I personally see RAs as ways to give fund managers guaranteed income. The fees are often ridiculous, and the growth middling. And if you make the wrong call, switching from one to another can be really painfull and expensive.
If I needed one, I'd look at the lowest cost option, made up of passive indexes. I think Sygnia has RAs like this, but I'm not sure who else does.
Out of interest, have you maxed out your tax free savings account yet? I think there's pretty much a universal agreement that those are excellent.