With Karachi having such a dangerous reputation, I would think more than twice before buying in such a place. Karachi was to become a showcase example for the future back in the fifties and sixties, but our religious and ethnic agendas destroyed all that! Lahore is the place to be!
Bhai, check the crime rate and murder rate. Lahore is higher than Karachi. At least that is what I saw on GEO's show FIR.
There are some areas that are bad in Karachi but there are also areas that are veryt peaceful. Compare to any big city of this size you will similar type of crime rate. Only bad thing that makes Karachi different is political violence. That makes Karachi worst than any other big city not to mention civic problems.