Cobra:
I need both the airbags and the RS9000s. The Airbags increase load capacity and/or level out your load. The shocks dampen the bounce. I have my shocks set at 3 front, 1 rear and 5 front, 5 rear loaded with my 5th wheel. Once, I hitched up 5th wheel and forgot to change setting on shocks. What a terrible ride. Truck was bouncing like a ball. I realized I forgot to change shock settings, and what a difference.
Plntmgr:
I don't see any cons, only pros. Makes your vehicle much more flexible in terms of ride quality and load stability. I highly recommend the Super Airlifts and the RS9000s.
All, happy trails, Wiredawg