My business partner, Eric, moved his family here, two young kids and his wife. Moving at night, even as a woman is very safe and commonplace in most parts of Kigali. It really is ridiculously safe here by any standard.
As an example, I am much less concerned about female friends of mine walking around alone at night in Kigali than I am my neighborhood back home in Seattle. (granted I lived in the CD which is higher crime, but still)
Is it safe for me, a woman, to visit there with my wife and kids? We've ruled out most of Africa in our globe trotting, but have really missed it.
I would say if you are visiting it wouldn't be a problem, definitely wouldn't worry from a safety point of view. If you were planning on moving here then I honestly probably wouldn't recommend it, not because of safety, but just that you would be going against the grain.
Is it safe for me to move to as a woman? Is it safe for me to bring my wife and kids? These things are often relative.