The idea that Cape Town is safer than Guateng is actually pure myth when you consider the actual crime statistics. As as the case with these things the socio-economic factors are huge in deciding what area you can consider safe.
THIS article give huge guidance as to where murder happens in SA.
While many people think that Johannesburg is the most dangerous
metropolitan city to live in, in South Africa, the reality is quite
different. Consider that between April 2011 and March 2012, police
recorded more murders in Cape Town than in Johannesburg and Pretoria
combined. This means that taking population into account, Cape Town
residents are almost twice (1.8 times) more likely to be murdered than
...almost two-thirds of the Cape Town murders took place in just ten
of the sixty police station precincts in the city, according to an
analysis of crime hotspots we carried out at the Institute for
Security Studies (ISS).
Research shows that most victims are killed by acquaintances, friends
or family members during disputes overwhelmingly fuelled by alcohol
and in some occasions, drug abuse. Victimisation surveys, police
docket surveys and mortuary surveillance studies reveal that the most
victims of murder in South Africa are young black men. And studies
reveal that most murdered women are killed by their intimate partners.
And that men are six times more likely to be killed than women.
People tend to focus on our national murder rate which is four and a
half times higher than the global average of 6.9 per 100,000 people.
Yet, some 13% of police precincts in South Africa have murder rates
below this rate. These areas include affluent such as Brooklyn
(Pretoria), Garsfontein (Pretoria), Camps Bay, Claremont, Rondebosch
(Cape Town), Edenvale and Linden (Gauteng). Meanwhile, residents of
suburbs like Sandton, Parkview (Johannesburg), Durban North, Table
View and Woodstock (Cape Town) and others have a murder rate of fewer
than 10 per 100,000.
Over 10% of our policing precincts – more than 115 stations – have a
zero murder rate. Three in four murders occur in just a quarter of
the country’s police station areas.
While murder is often used as the main indicator to support arguments
that South Africa is a violent country, it makes up only 2.5% of all
violent crime. While there were 15,609 murders last year, a total of
607,877 other violent crimes including attempted murder, rape, robbery
and assault were also reported to the police. When violent crime
hotspots are analysed, central business districts remain the most
high-risk areas in terms of violence in general, and specifically for
robberies. The clear front-runner is Johannesburg Central, followed by
Durban Central, Pietermaritzburg, Cape Town Central and Pretoria
Central. These areas also experience very high property crime rates.