Unless I have missed something, the military aircraft with OLEO struts can take a LOT more rate of decent than ANY skid, at least in normal landings (I dont typically crash land each different type I fly). I can tell you that a FIRM landing in an SH-60 on a ship would be a catastrophic airframe failure on a jet ranger!

Speed limitation on helicopters is NOT due to landing gear , but to maximum speed a on blades. Remember the helicopter spin its blades to obtain lift, when the airplane is tracted by it propeller. Hence the zero airspeed stall existing for a helicopter (hovering).
The speed affecting the blade is calculated by adding the airspeed to the blade proper speed for the advancing blade, and by subtracting airspeed from blade own speed for the retreating blade. This airspeed difference is also a lift generation difference, which is controlled by the flapping hinge of the blade.
This flapping hinge has limitations like to not hit and chop the tailboom, ouppps.
The fastest helicopter in the world is a lynx and has the advantage of having a rigid main rotor.
At speed over 200kts the flapping hinges are starting to have difficulties to compensate difference of lift between advancing blade and retreating blade. This is why the idea of the X3 is to use propellers to move the helicopter and slowly reduce the main rotor speed – which lost of lift will be compensated by the small wings.
Many solutions to obtain this have been studied, V-22, Fairey Rotoryne, etc. the X3 is based on the same principle the fairey rotodyne and should be more succesfull than the V-22 because it is not using tilt rotors but a single main rotor to provide lift at low airspeed, and will have a same aerodynamic reactions as a normal helicopter.

http://www.youtube.com/watch?v=LxhogYKwV7Y