I as well upgraded and have had some troubles. I haven't had outlook calendar integration troubles, but had troubles dialing out at all. What we had to do was go into the users profile, roaming folder (Windows 7) and into Mitel folder. We zipped up the UC folder and then deleted it. Open UCA and it would create a new UC folder and work fine after that. Apparently there was something wrong with the upgrade path or something.
Downside..... Users would lose their contacts. I am working on trying to get some of those back. Some have worked by going into UC zipped folder that I kept and grabbing the contacts group and contacts files, but not for everyone.
So I didn't really answer your question, but gave you something to try. Find a user without personal contacts and try it.