The Append tool has the Update Features option, allowing the user to define fields to match the input data to the target data, and where features in both datasets match, those features are updated instead of appended (avoiding duplication).
IDEA: Add a toggle box option as part of the Update Features function that removes and features from the Target dataset that don't have a matching feature in the Input dataset.
USE CASE: This will be handy where a dataset should be a complete copy of the input dataset, but currently requires 2 different processes to achieve this. Either Append (to add new features and update existing matching features) plus a Join > Filter > Delete Rows process to find and remove any old features that are no longer relevant. The other way of achieving this would be to delete all existing features and appending the complete new input dataset. I want to avoid this though as we're talking thousands of records and that is time consuming when dealing with feature services in ArcGIS Online.
