I just upgraded my live site to vB and I have the bridge running to connect it to eFiction 3.0. So far I have not had any issues with it.
eFiction 3.0 is still in beta though, and I am a bit hesitant to release the bridge until it goes gold.
I have a few parts to the bridge now. The first is the user info sharing to give you a single login for the entire site. This is now based off of user ID, making things much easier.
I also have a skin sharing module that exports the skin from vB to eFiction. This is still in development as it is quite buggy...vB skins do not like being outside of there home directory

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I am also working on some Zoints Local blocks to pull data from eFiction over to the profile page. This is still early development though.