RE: Sight Pin Spacing..
^Exactly. Once your arrow reaches the highest point of trajectory (say 10 yds) from then the gap in ten yard incriments is spacing out more and more.
Come to think of it, my buddy that i shoot 3d's with xforce hunter setup is a 4pin site, and all of the pins are sooo close together. the cluster of the pins is what really makes them all look like the same gaps though.