agree with the above 2 posts. the sway does take alot of the stresses encountered with trees, roots, humps/bumps, or other obstacles. the other day i hit a well head on a customers property. just caught the side of the bush hog luckily. it was hidden in deep golden rod. i was going along and suddenly, bam!!! by the time i got stopped i was about 3 feet past point of impact and could barely see what i hit in the weeds. it was their water well head and i caught it on the condiut and wire side too. no damage done to the well head wires or my equipment and the extra slack in the 3ph i am sure helped me out by letting the bush hog shift out to the side instead of putting full force at the point of impact.
just for a bit more info for your thoughts, i used to (for about 2 years) hook those 3ph chains so tight there was no mavement. never had a problem, never broke anything, but since i have been leaving some slack in the check chains of 3ph, i also have not noticed much difference in their use of efficiency. either way not much difference with bush hog cut and you get the benefit of the sway off striking potential obstacles. i am not sure if mine is quite 2 inches though. probably little less then that, but still some slack.