Never bought into the more power and torque thing. It's just depends on how much the blasted thing weighs. You may have mor power and torque but will it be enough to compensate the extra 200-300 pounds and $$$. The only advantage would be if you two up a lot and need a little more room. That is how I got my bike because the previous owner started to ride a lot more and farther with his old lady and needed a bike more suited to their riding. Love our bikes but the comfort level on long distance two upping is just not there. That no problem because my wife rarely rides and I mostly keep my ride solo. But if you two up a lot then the 1500cc(if it ever comes!) will probably be your bag.
