Yes there are two or three aircraft that do this. I've modified the A380 in flightgear to use three groups with different times.
I'm not near my desktop at the moment but can send you what I had modify to make it work.
If you wanted detailed realism you could make different config for each gear and add a small offset depending on hydraulic pressure which could have some random filter applied..
Is it possible to specify gear up and down transit times for each gear? In real airplanes the gear never ( well rarely, maybe ) sequence in perfect unison. In reviewing the xml files for the 737, I note there are transit times defined for each flap position, but the kinematics for the gear is only a single value for up or down based on gear selection state.
Is this something in Nasal? or native code or something in JSBsim?