I have both. My Ninja extreme spread is under 10FPS (1/3 that of the JDS with no creep over night or at FULL pressure of 3626psi)
Measured output with a Wiki Gauge and the Ninja regulator is pretty much instantaneous recovery.
The JDS Airman one took 6 Seconds to get w/i 100psi of set pressure, 17 seconds to get w/i 50psi and a full 35 seconds for full recovery.
In addition the JDS would "creep" up in pressure over night, sometimes as much as 200psi.
Here is a link to my testing in my Flex
http://www.gatewaytoairguns.org/GTA/ind ... c=110281.0
Here is the pic of the Ninja piston vs the JDS. Luckily for about $12 you can replace the JDS piston with the Ninja if you already spent the $100 plus on the JDS.
http://www.gatewaytoairguns.org/GTA/ind ... 1229;image