I have the same question Harry. Even if I do loose it it's not that big of a deal. As I will just get that back quickly except on WAW. There I will have to re-earn everything back I believe but I may have to call for assistance on that one!
It should be fairly simple to change it in game. Make a backup of your .cfg file, open it with notepad, hold Ctrl key and press F key. type in part of your name and press enter. it should find your name in all the jumble. change your name, leaving all other characters before it and after it unchanged, be sure not add any extra spaces in the code. save the file back to same place it came from. when you open your game, you will still your old names on the load profile menu, but in game it will appear as you changed it and you won't have to start over on your earnings. this is how I did mine when I got my >XI< member tags