@magicalclick: Assuming you were not attempting to write drivers in C#, what about it is slower or supports less hardware than C++? (Of course, I'm assuming you are still targeting Windows...)
Case studies tend to show that C# produces better performance than C++. I've seen where people have set out to show how bad C# performs compared to native code, and change their minds once they see the results.
This isn't meant to troll, but I'm genuinely curious since this is not the typical path taken.