Has anyone successfully modified the current.gpx

That file is only a copy of your favorites. You need to add, delete, modify through the menu on the unit itself.

Make sure the encoding statement says encoding="UTF-8" (and make sure the file is actually encoded that way - Notepad, for example has a dropdown list of encodings, but defaults to 'ANSI').

Note that you can only add new entries; you can't edit existing ones. Also, when used as a Favourite, only a small subset of the fields are used - the rest are ignored.

(Strictly speaking Current.gpx is an output file ... it just happens to get caught during the scan for new input files, when the unit boots. Any new entries in .gpx files are added to the internal list and the .gpx file deleted. Then, the new internal list is written to current.gpx, overwriting its previous contents).

How then, do I edit the address of a stored favorite? For example, the stored entry for my work shows the coords instead of an address.

I think the answer is: Experiment!

There seems to be some variation between units when dealing with Favourites, in the same way that there are variations when dealing with Custom POIs.

Trying looking up an address using the Nüvi and store it as a Favourite. Have a look at Current.gpx and see what fields it used. (Take a copy as current.xml and open it in a Web-browser, for a readable 'tree view').

Personally, I don't make much use of Favourites, except for short-term navigational purposes - and recording the coordinates of a location, for further use as a Custom POI.

The only problem I have with using the custom POI's is the extra 'Custom POI' menu I have to click. Is this really neccesary? Is there a way to move my Custom POI's up a menu level?

I think I loaded the current ones from MapSource. Maybe that is how I got the addresses loaded in.