Being even heavier than Craw, I can feel flex in everything also. I'm 240lbs and on XL or XXL frames and have had trouble with component and frame stiffness for years (never a problem with strength though). I love some of the newer, stiffer carbon frames, burlier XC forks, 35mm bars, beefier cranks, etc. Along with the trend to longer frames, the increased stiffness of frames has me completely happy with the fit and ride quality of my bikes. Finally!
I've used all varieties of XTR cranks for years and I've noticed that the latest M9000 lacked stiffness in torsion and bending. When putting the power down I can feel the crankarms twist which causes an odd droop in the pedal which I can feel through my shoes (stiff carbon soled shoes). Even worse is that I can get the crankarm to clank into the drive side chainstay of my XXL Tallboy 3. At first I thought this was a combination of flex in the crankarm and flex in the frame but this went away entirely when I switched to Next R cranks. The Next R cranks sit closer to the chainstay by 2mm so that's not the reason for the problem. After putting a bunch of time on each setup I'm sure difference is due to the combination of stiffer crankarms and spindle of the Next R cranks.