I really miss the ease and capabilities of Union as an editing tool as opposed to merge. For my usage, I have multiple sections of the same polygon or line features that get drawn separately, with their own unique inspection photos. Without Union, I am forced to go into Web Editor, download the photos of every segment, and then merge and upload all of the missing photos.
With Union, field users could combine different sections themselves and maintain all photos. The new editor tools are not nearly as useful or easy to use for field staff.