Butcher,
Here’s what I found out…
You were right about the Multi-Author list, but in order to actually change an entry by a particular author you must first change the entry options author to the new editor who will be making the changes under the options tab, then can go back and edit the entry.
The only other detail I noticed is once the entry is saved the editor needs to go back and change the “whois” author on the article back to it’s original owner/editor.
Outside of this I haven’t found a better solution which would allow the editor to edit the entry by another author without actually changing the “whois” dropdown data and saving as its original author, without actually having Super-Admin privelages, so it looks like that’s exactly what you were saying.