Eai are just rebadged Parker cylinders. If you want to go with cylinders and want top of the line look into Canover. They use a system of check valves and expansion tanks (accumulators)to make it ride better than the usual cylinder set-ups. Usually cylinders replace the shock and spring assembly leaving a very bouncy ride. At the top and bottom of the cylinders motion you usually get a noise or a bang where the suspension just wont move any more. They are also prone to leakage over time. Overall, they arent really practical.
www.canoverair.com