I will be the odd man out.  We have a double alley off a Bud Box and I would rather have a single alley all the way to the chute.  Our cattle like to follow each other, not walk beside each other, so they will stand there with their heads all jammed in one side while the other side is empty.  When there is room for one more the animal will almost always try to climb on top of the full alley instead of walking into the open alley.  An additional problem I have with it is my own short arms.  I can't reach across the one side to inject the animals in the off side alley.  Having said that, when compared against a full sheeted curved alley fed from a tub, it works great.