My main concern on the managed compiler is the performance, you know, like Herb and Charles said, if you want reeealy good raw performance, you should go native, and compiling is really a performance critical task, how does the 'Going Managed' work ??
as Eric Lippert said 'the performance of the entire analysis engine is not as high as we would like ', so what are the pain points and what's the plan to get the performance back ? do they need some really unatual dirty tricks like people do in XNA stuff ? what's the difference in performance characeristics of the native and managed compilers ? like 'which one is good at what' stuff.
actually Eric has answered many questions in the comment of his post, he is in good communications.
I feel like Roslyn is the 'Kinect SDK' in some sense, I would expect some magical 'cool hacks' from it.