There was an article somewhere a couple years ago about a test between sport tourers, and the camera/chase bike was a R1200GS. By the end of the weekend, all the riders involved in the test agreed that he best sport tourer they had ridden was.....the GS.
I think the point is, unless you are planning on traveling at high warp speeds on the interstate for days on end, an adventure type bike has a more comfortable seating position, better suspension, handles just as good or better in the twisties, and can explore those gravel and dirt side roads without the fear of scratching the $hit out of your fairings if you drop it in the gravel at 2 mph.
Found that article, there's a link. Pretty good read.