Originally Posted by intr1gue
So after two R1200GS's I swapped down to an F800GS when I started riding more aggressive offpavement/offroad stuffs. And that's the ONLY reason to switch. In my mind the two bikes are not really bigger/smaller, but tools that favor one kind of riding over another. If you're willing to trade offroad ease for onroad comfort, get the R12. If you're willing to trade onroad comfort for offroad ease, get the F8. Simple as that. There's a host of tradeoffs beyond that (gas mileage, height, electrical farkle power, etc.) but honestly that's the only reason I could come up with that actually made sense.
Figure out what kind of riding you really do, and then get the bike that makes that easiest. Then go out and ride it =)
+1. Ancillary stuff aside, looking at them both predominantly as "bikes" and the main differences in riding experience associated with them, this is my verdict too.