being a karachiites, i feel no fear roaming everywhere in normal days...but no one can say for sure when this normal gonna turn into ibnormal 
As you are an outsider and thanks to our media jo har khabar main mirch masalah laga daite hai so seeking a safe place for u is ok. There are several guest houses at shahrae faisal which are safe as well as affordable, if you would say i can provide you detail of the one.