When UpdateDetector routes features to DELETED, ADDED, UNCHANGED it is pretty easy to understand why. But when routing to UPDATED, the reason may be geometry or changes in one or many attributes. Sometimes the differences are not so obvious, ie spaces, different data types.
I would like an output attribute stating the reason for update, and also attribute output with a list of the attribute names that caused the update. This would also make it easier to look for different types of updates for logging or stats.
For performance reasons this could possibly be turned off.