I would stick with the air shocks as they absorb and disperse the shock better than the hydraulic ones. Fluid would transfer too much of the shock and you would definitely feel it. From a strictly analytical/scientific perspective, fluid & air/gases are basically the same in that they react in the same relevant manner. Fluid is denser, so it transfers more of the motion, or in this case shock/motion, more effectively. Gases absorb the shock better because gases are infinitely compressible. Common hydraulic fluid compresses .01% at 10k psi. It transmits the shock whereas the air/gas absorbs it. Just my opinion...