I would add to this discussion that a super stiff frame is not much fun to ride. Given that some 120lbs riders are touring with 30lbs of gear and some 300lbs riders and touring with 100lbs of gear the amount of stiffness needed in touring bikes varies quite a lot. I've owned a number of different touring bikes ranging from noodly to ultra stiff. I didn't love the ones at either end of spectrum and settled on a middle of the road stiffness touring rig in the Surly LHT. Which makes sense given I weigh 175lbs and tour with 30lbs of stuff.