I think user choice is essential. I think that this idea that people who are using the Insider Preview, who do not have a valid version of Windows 8.1, may have to choose between continuing to use the Windows 10 Insider Preview or staying on Windows 10 general release (when it comes out), is a false choice. Microsoft should, ideally, and even in their own interest, allow users with administrative privileges on a machine or a domain controller to opt-in or opt-out at any time. This similar model is used all over the place when it comes to software development. I like the idea of kernel updates potentially coming straight from Windows Update, but the ability to defer individual updates, or prevent them from being applied at all, has been essential for IT managers around the world. It will become a major issue if and when adoption to Windows 10 by businesses large and small becomes a reality. The problem really is a stinker for what is turning out to be a great OS, especially since what we saw in build 10135, I have to say that even I am impressed.