Interesting. The only thing not working in my setup is the quota function. I too patched postfix, everything went fine, but I see no indication that quota is working.
In fact I am using the quota_notify script and it indicates no quotas on anyone. The Daily Quota report just has the header but no list of users & quota %.
Note that I did decide to bypass delivery into the maildirs with Postfix and use Maildrop instead since I wanted to do some advanced filtering. Could this screw something up?
When I looked at the link you suggested, I saw nothing that made me think the situation there was applicable.