I've always had the same concerns about the M-10 as every other aggressive rider (loss of topend, no transfer) so I always said no thanks. But after riding and comparing the Airwave side by side to an M-10 there are some definite differences.
Topend loss- this is something that has become less and less of an issue as the OEM skids have become almost just as tall as the M-10 over the years. What used to be 5-10 mph loss is now closer to 2-3 mph.
Secondly, the neat thing about the Airwave is with the touch of a button you can lower the skid to drag-race height, pretty much eliminating the aggressive approach angle of the track. I've actually seen a 2-3 mph gain when trying this.
Weight Transfer- When jumping from an M-10 to an Airwave I did notice more transfer, not as much as some OEMs but definitely a quick, controlled, shift of weight to the track. No more sit and spin as the M-10 did.
This is accomplished by spring position on the rear torque-arm. The air-spring is mounted more perpindicular to the arm than the M-10. When one applies torque to the track on the M-10, it has to fight all the spring force in that massive coil spring before it can slide the coupler blocks. On the Airwave, the air-spring can tilt back and forth with hardly any effort, allowing the torque-arm to slide in the coupler-slot with much more ease.
I've even heard of guys running w/o a limiter-strap being able to pull the skis a good 6" to 12" off the ground!
Air-spring vs. Steel spring- After studying and testing rolling-lobe air-springs for a few years now, I've found they will ALWAYS out-perform a steel spring in all critical areas- isolation capability, bottom-out resistance, and range of adjustment.
All other variables being equal, an air-spring supension will have a much LOWER NATURAL FREQUENCY than one that is sprung by steel. What does this mean? Every sledder probably has realized the effect of getting a smoother ride by actually riding faster over a rough trail. What they are actually doing is changing CPM of the FORCED FREQUENCY. The farther they can raise the forced frequency above their suspensions natural frequency the greater the isolation capabilities of the skid.
This effect gives the Airwave a huge built-in advantage. In order for a steel sprung skid to match the low natural frequency of the Airwave it would need a spring length of around 20". Good luck fitting that in a sled suspension!
Air-springs also have a great advantage in bottom-out resistance. Their spring-rate is a true progressive rate that rises exponentially. In comparison, steel springs are either straight-rate or multi-rate. Even the multi-rates aren't truely progressive because they are really just two or three straight-rates stacked on top of each other: more of a step-rate actually.
Hope this long rambling post actually clears up any misinformation out there about the Airwave. Since I've never ridden a ZX-2 I can't really make fair comparison other than they both weigh about the same- 53lbs.