Did anyone with a dual boot configuration already try the upgrade? This article [1] suggests that, for once, you don't have to restore GRUB after the upgrade.
This really surprises me. The SHA2 code-signing hotfix released for Windows 7 a few months back won't even install if you dual boot. I still haven't installed it.
[1] http://answers.microsoft.com/en-us/insider/wiki/insider_wint...