M, I only reapplied Rollup 3 just in case uninstalling Rollup 4 left any residual...more of a superstitious reason than a scientific one. But no, I didn't run into any other issues. The whole process took me about 30 minutes so hopefully you won’t have too much down time.
Scott, I am certainly no expert on the matter. All I know is that the Event Viewer started reporting that beremote.exe was preventing some of the Exchange files from being changed and the uninstall of Rollup 4 seemed to have hung at that point. My solution was to stop and disable the BE services and shortly after the uninstall progress bar started moving again. On the other hand, it might have been a complete coincidence. I am not a guy who likes to wait on progress bars:)