You must disable the Ubies studio repositories and all 3rd party
repositories before upgrading. The result would be a Kernel Panic error and
there is no easy way to fix it and you'll be ending up doing a fresh install. To
edit you resources list go to the Terminal and

gksudo gedit /etc/apt/sources.list

Use 2 # signs in front the Ubuntu Studio lines
for example
##archive.ubuntustudio.org/.../Pac\
kages.gz404

Okay, I unchecked as much of what you mentioned as I could find (via the ##
mode or by unchecking them in the other system submenu thingy).

The current hang up with the upgrade goes as follows (in terminal):
ldconfig deferred processing now taking place
Errors were encountered while processing:
compiz
compiz-gnome