I had the upper back pain with stock bars - also coming from a DL1000 which didn't give me that kind of pain. Swapped to Moose CR-Hi bars (same ones I had on the Strom), found they were too low for standing on the S10 - added some 30mm Tusk risers and now getting some forearm pain. Hmmm. So still fiddling the the bars. I have some 2" Rox risers coming this week.
I rode a mate's S10 with stock bars a couple of weeks ago, and the upper back pain was back, so that just confirmed where that problem was coming from and that I need to persevere with other bars.
Moose bars compared to stock - straighter and lower. Plenty of aluminum bars to choose from, but I wanted steel because in a worst case scenario, they can be bent back into shape (I once endoed an R80GS, right bar was bent at 90° but with some heat added was able to get it straight and rideable). Plus they are much cheaper than most aluminum.
http://www.chaparral-racing.com/Product/moose-racing-carbon-steel-cr-hi-oversized-1-1-8/M0601-1799.aspx
Rox 2" risers
Will report back after trying the risers next weekend.