The GB has a longer base, front to back than the coyote and is intended to rest on the rear of the seat and rack. It could be positioned more rearward, but is likely keep a passenger from getting enough room between the bag and yourself, for comfort.
Coyote is the rear fender/rack mounted unit.
The Fort Rock is a top case for panniers and not a stand alone bag.
The new Siskiyou Panniers would be the most passenger friendly high volume alternative in the line.
Harold just posted some 2013 pics and discriptions in the Vendor's forum.