I have been To Johannesburg and neigbouring Pretoria. Have travelled to South Africa about 20 times studied around Cape Town in 2003 2004 and Worked in Durban in 2010 2011. Have many friends there love the country love the livestyle. Would hesitate to move there(country) with kids, would not wan't to live in Joburg with wife and kids. Joburg is dangerous its the rape capital of the world as said get used to hig fences barbed wire, bars in front of windows, caarying pepper spray on rides. Have woken up with a knife against my throat and been attacked on my bike several times in the safer western cape.
Though its a lovely holiday destination, the have an active ride scene and beautiful overwelming scenery in many places. Must book a ticket for another visit still have a spare bike somewhere down there. http://www.thehubsa.co.za for cycling info road is keen MTB wonderfull. Though inform yourself where you ride some are's are no go others only in a group. I have been asked to hang back and wait for some ladies in a race as they ran out of armed escorts for part of a mtb route.
To put it in perspective I have been the most scared in my life in Johannesburg. I currently live in Rio De Janeiro and cycle along the edges of the Favel'as I have worked in one of the most dodgy streets in durban, Lived in Mozambique lived and worked in Helhole Luanda Angola, worked in Angolan bush but only in Johannesburg I am afraid of my own shadow. So No I wouldn't especially if you are used to Switserland. Especially as the country is becoming more unstable with farm and mining strikes(some of my mates had part of their farm burnt down and flew the family out with the chopper that brought the mercenaries in). Also Mandela's health is faltering its a big worry as his death is expected to be the spark to ignite quite a bit more violence.