So I just re-installed the upgrade PBI. Of course, it wasn't that simple, so I wrote about my experience in my blog:
A couple of things that I consider bugs in the upgrade PBI:
1] It reboots the computer with nary a warning. After installing, you just get a dialog box saying "Rebooting..." and off it goes. At the very least, there should be an Okay button so I can save my work first:-(
2] It shouldn't overwrite xorg.conf. Or at least, if it must (it actually deleted mine and created a link to XF86Config), save a backup copy.
And I don't think it edited my rc.conf file, which, if it wants to run hal, it had better.