I'm currently running Ubuntu 11.10 and would like to upgrade, but the upgrade manager wants to remove several packages, such as Cinnamon. Is it possible to upgrade without it forcefully removing these packages and changing my UI to the Unity interface?
When Ubuntu upgrades it disables third party repositories and PPAs. Sometimes (but not all the time with certain packages) it will need to remove these packages in order for the upgrade to proceed.
In certain cases like Cinnamon (which I can see is in 13.10) an inplace upgrade is possible, but that really depends on the differences between the packages in the PPA and the ones in the distribution.