Solution:
Logic uses a caching system to validate Audio Units such as Superior for use in your project.
This process, unfortunately, can be temperamental, particularly following updates. This can lead to the number of outputs being incorrectly recognized (Superior may only appear as a stereo or mono insert).
If you experience issues after an upgrade of either Logic or Superior, please try in the first instance to delete the following files:
/Users/yourname/Library/Caches/com.apple.audiounits.cache (Logic 8/9)
/Users/yourname/Library/Caches/Logic/com.apple.LogicAudioUnits.plist (Logic 7)
If problems persist please repeat the above and refresh the Audio Unit manually by following the steps below:
1) delete /Library/Audio/Plugins/Components/Superior Drummer.component
2) rerun the latest update available from the ‘DASHBOARD‘ section in your account
If all fails please file a support ticket using the online form.