I've ridden the S10 and liked the riding style and features, but I think the S10 and GS are too heavy to be dual sports unless driving on gravel constitutes dual. I've been on quite a few gravel roads with the FJR two up and had no problem, add a set of wider bars and the handling would be greatly improved.
That's an opinion which is far from fact. The fact is 1200GSAs are VERY capable off road. I have seen those bikes go all over the place.
When I went to Big Bend, it was with BMW riders, including the Sales manager and Service manager from our local BMW shop. There wasn't anywhere I took that 250 that they didn't take their 1200s. I was however , the only Yamaha there. I was also the only bike that couldn't go over 60-65, and I was the only one that ran out of gas.
Because of weight and the front wheel, sometimes they had to work harder, but those bikes have about the same power to weight ratio as smaller bikes. All they lack are the riders with the ability to ride them.
Don't believe me? PM Patch308. He's my younger brother and rides his everywhere. Maintenance on his BMW is actually easier and just as cheap as my FJR. Today's BMW is not the BMW of 20 years ago, but some people can't let it go. There's a reason the BMW GSA is the most prolific dual-sport bike in the world.