I find it interesting that most of your points in favor of Xcode are just because of the clang backend, while the points for Visual Studio are more about the IDE itself.
Would be interesting to hear your opinion again, once clang is fully supported through Visual Studio.
Yes, I noticed this too while writing the points down. It really comes down to the clang back-end. I'm really looking forward to the clang integration in VS, and also really love the work MS is doing to fix Android native development.
One strange thing I see with clang running on Windows (in the form of the emscripten fastcomp backend) is, that clang runs a lot slower on Windows than OSX or Unix. So may be it is some underlying IO problem? I'm not sure but hope this can be fixed.
Would be interesting to hear your opinion again, once clang is fully supported through Visual Studio.