Gilgameesh
This sounds a good way i didn't know it existed.
Of course this works great if you don't have to personalize something (ie: macro that need your name).
So, if you change something, it will change for every character.
I would prefer save/load and the freedom to personalize it later on, just in case.
If you think of character names in macros like "careplaning", just put the names like this here in:
<command name="target" params="entity=heernis|quiet=true"/>
quiet=true means that it will only show in sysinfo, if the char is there. It is pretty easy.
I don't think loading different files ingame is really a necessary. I have no idea in which use cases it could be useful. ;-)