It is important to have very clean and well-organized .fla files when you work in a team. At MediaMonks, we have naming guidelines which should be used by all monks.
This tool is made to easily assign or change the class of a MovieClip, and uses our naming standards for the linkage names (which is filename dot SymbolName). It also gives you the option to change the instance name over the full timeline and fixes the layer name. The tool has a class-dropdown, pre-filled with Temple-classes, and the classes that are already linked to library symbols in your current document.
I use this panel as complete replacement of the symbol properties window, since it is smarter and less annoying.
Find all my JSFL tools on Github.