The 1200 GS not only has dual plugs, they are electronically controlled to fire separately based on engine speed, etc., which is supposed to alleviate the surge as well as make the engine able to handle lower-octane gas without pinging. The engine also has counterbalancer to get rid of the "boxer buzz," though I have never found vibration to be a problem on my R1100R (OK, it vibrated like crazy for the first 5,000 miles, but not any more...). The bike also weighs about 70 pounds less than the 1150GS, which should make a big difference, even bigger than the advertised 15 extra horsepower.