The YM2000 would likely win because of more motor under the hood and that Low 1st is a heckuva pulling gear...
I have very rarely not had enough power with a compact tractor. Virtually always, the limiting factor is traction. I'm a big fan of the 2000's engine, don't get me wrong, but the motor isn't going to be the determining factor in a pull off.
As Carey pointed out, the risks involved in tethering a tractor to anything and seeing what happens are severe. The story he referenced is a tragedy, and something all operators should read. A boy, working with his grandfather, was pulling posts using a chain wrapped around the post and through the wheel disk. Driving forward lifted the post out of the ground. One post was more secure, the throttle was up, and the boy let out on the clutch. The post didn't move, so the tractor did. It reared over backward. The machine DID have a roll bar, described as well built by the investigators, but the cast axle housing
fractured. The roll bar collapsed, the boy was crushed, and died. Obviously, the grandfather and everyone else were devastated, since there were multiple alternative courses of action that wouldn't have resulted in his death.
In soft dirt, pulling the same plow, my YM2000 out pulls my YM186D. On harder soil, I think my 186D pulls harder. I haven't yet quantified that.
Don't do it just because you have them and find out Not So.
