I just don't get all this hype bout 450's being "easier and less tiring". I rode a dude's 450 XC and he rode my 02 yz250 the other day. First thing I noticed, as I notice on every 450 I ride, is how dead and flat the suspension feels. But my arms were immediately more tired riding that beast then my 250. The trails were whooped out sand with perfect bermed sweepers. I know for a fact I am very much faster on my 250 then I ever could be on a 450. And when we switched back his comment bout my bike was he was surprised at how much power it has. It's an 02 YZ250 with an 05 Cyl. and a fatty pipe. Nothing else. Just because they have more torque, they have more girth to throw around and to me they are harder to go fast on when you actually have to turn at speed. Just my opinion..
It's not that they are easier to ride...it's that it is easier to put the power to the ground and application of power. For a less skilled rider, they can just turn the throttle and go, no need to worry about tire spin, clutch release, or proper weighting. Putting the power to the ground is 90% of the game.
Actually, that is one of the reasons the mags all claim the 4$ is faster. If you put a pro rider out there, he is going the "ride it like a 2T" with slipping the clutch in the corners, rolling one the throttle for maximum traction, and proper riding techniques. The few extra HP that are available to the bigger bore 4$ are going to make themselves known in his lap times. If the mag put a C rider out there, his lap times would be faster than on the 2T because the application of power to the ground is easier. More hookup. More speed.
Like you mentioned, the quicker and lighter "feel" of the 2T make them "easier" on the body but then to go the same speed, you have to work it more.