B7100hst-d w/turf tires, and approx 100lbs on (f) bumper, and can mount/run 5' blade on 3pt with no difficulty, but once the pushed load gets very heavy/much, it gets worse.
I usually attach my 4' box blade and am much happier with the performance
I ended up getting a 5 foot rear grader blade. It weights 250 lbs, and seems to work pretty good. I have a FEL as well, so this really helps even the weight out. We will see how it does in the snow.