Either one gets you a nice ride improvement due to the big body and 60mm piston, but the difference is the 8112 having hydraulic bump stops on both ends. If you like to go really fast off-road, get the 8112s. If you don't like to party, get the 6112s.
Another factor is the 8112s being...
I think you'd want to go with fiberglass fenders in order to let the position-sensitive nature of the 8112s run in the correct ride zone. If you crank them up too high, you'd just be in the RCO all the time.