Terri, it might change the pressure points slightly when the horse is moving at liberty without a rider, but with a rider, the entire bar is being pressed down anyway so there's not much difference there between the riggings. However, changing the rigging might change how the saddle moves with the horse. For example, a horse that was being rubbed on the loins in a "full" rigged saddle, might not have that trouble anymore with a centerfire rigging because there's not as much side-to-side at the back of the saddle.
As for cleaning cinches, I've got one of those $20 water jet pressure washers from TV. I use that until the water runs clear. If I've got a lot of hair on them, I'll gently use a rubber curry comb to work most of it out.