Upgrading to EC05 caused my Epic to lose the ability to sync fully with Microsoft Exchange. Email and contacts sync, calendar does not. This is known issue throughout Android phones (all kinds of posts all over the internet for the last 18 months -- with no answers). Apparently a system update can cause it.
I'm just one of the lucky ones affected. It has to do with the architecture of the Android OS and its lack of complete integration with ActiveSync.
I've tried everything from hard resets, factory resets, wiping, Odin, different installs of EC05, rooting, non-rooting ... nothing works. There are some purported Exchange server potential work-a-rounds. That's my next stop.
Unless and until Google provides stable syncing with MS ActiveSync, they will not be competitive with business users (and "no," I don't want to use TouchDown as substitute for the built-in ROM calendar app). That's very unfortunate for Android and phone users.