I have also been eyeing that crag for quite some time now. Have asked around a bit and everyone I spoke to that knows that area advised against it. Seems to be in the "dodgy" area of Mamelodi.
There is a crag closer to PTA also on that road near the prison which also doesn't see visits anymore due to crime. I believe there was an attempted murder on a climber afaik.
There are a couple of nice grags close to my house, but they are all on posh private property, so access will be a problem. This is out on Atterbury road.
One place that I have climbed at, and totally kicks Struben's Valley's ass is located just North East of Pretoria. Faces there are as high as 30M in some places, and there is potential for about 100+ routes plus bouldering. I used to live close, so I frequented the place quite a bit. The previous owner sold the place, so I'm not sure about access these days. (I could phone them and find out). This is really an awesome place with a bushveld feel 20 minutes from Pretoria. Be prepared to trad or rig anchors from trees and rocks. I am also interested to go out there again so give me a shout.
That is all the PTA climbing that I know about.
Let us know if you find something cool.
Crags out on private property attebury way...sounds interesting, I live quite close to Menlyn mall. Mind posting the details of how to get to the crags NE of pta, might be worthwhile to go out there and see if one can chat to the land owners about access.