[CWSpear13]

Is there any stopping the update once it's started to move stuff around to get a better start...? Probably not, eh?

[PatrickTulskie]

You can hit cmd+q from the screen where it's doing the install and it will quit out and let you reboot back into your OS.

[jlindley]

Not that I know of. If you find a way to do that I'll add it to the post.