I have the XR400, but rarely ride it, it's not losing value or costing me, and I like it so I'm keeping it. I ride it once or twice a year, really.
I am, however, entertaining the idea of getting another bike to share the load on the GS. Since I intend on keeping it forever, it sort of makes sense... The only reason I haven't gone test riding other bikes is that for now I can't see myself going for a proper ride and leaving the white bike behind.