Interesting - I've just come back (yesterday!) from a six week trip to Iceland on my GS. I rode a little over 4,200 miles whilst there, about 60% of which was off-tarmac on gravel and dirt roads.
I'm writing this up at the mo, but if you'd like to see some pics in the meantime, you can do so here:
Iceland Photos.
Make sure you select "full screen" as these are hi-res so it's worth the effort!