If like me you are interested in code quality and some general conclusion that one can draw based on code quality studies, I really recommend to read this paper: A Tale of Four Kernels by Diomidis Spinellis, ICSE '08: Proceedings of the 30th International Conference on Software Engineering

I just want to quote a part of the conclusion by the author

Therefore, the most we can read from the overall balance of marks is that open source development approaches do not produce software of markedly higher quality than proprietary software development.

The only problem with this statement is that it is based on the fact that the metrics he used were not weighted for their importance for the "Code Quality" (if this means something). Therefore, the comparison between the Windows research kernel and Linux seems a little bit awkward to me. Anyway, this is a very interesting paper about code quality, and lots of interesting ideas from the author of CScout.