I have list of all open and closed maemo packages, also list of all preinstalled packages. See: http://talk.maemo.org/showthread.php?t=75174
write which package is upstream, which upstream + nokia specified patches and which are nokia's packages. Obviously you cannot remove nokia specified patches...
If you want still use udev, then you must have / and /usr on same partition.
why do you think going straight for Wheezy is not an option?