You can also specify a navit.xml to use when loading. I use Personal Menu / Personal Launcher and edit the command to read

navit /path to/navit.xml in my case: navit /media/mmc2/maps/navit.xml

That way I was able to quickly start either internal or use navitgtk.xml (navit.xml edited to use gtk interface) to start the GTK version. I also do that to try different settings for the OSD when editing navit.xml, or load different maps without having to edit navit.xml every time.

More advanced, i used the xinclude to break out the setting into several files to make it easier to edit. I have maps.xml, poi.xml, osd.xml, and a couple others so I can quickly find only what I want to change (and not have to edit both navit.xml and navitgtk.xml to keep some of the settings consistent). Probably more trouble than it's worth though.