dear fragtion.
We have extracted the newest annex B firmware from a router (this FW is only here availiable)
If the router works good with the new unbranded firmware, you shouldn't put a new one on it.
for a complete unbranding you should make a root access for the router
english tutorial here:
http://bcsaba.net/?q=node/5
when you are logged in the SSH as a root user, you should type these commands:
cd ..
cd ..
nvram_util set customer = 0
When you make this, your router is completely unbranded from any provider.