The electronic box is a neat idea, but as Vincent says it offers protection on switch-on only, not subsequent accidental bumps.

The weight-on switch mimics full size protection somewhat, but on a bumpy grass runway the gear could retract after hitting a bump.

What about a climb sensor that inhibits gear up selection until a sensor observes a climb of 3 feet or 5 feet. Are they that sensitive and reliable? I really want the gear up that quickly after takeoff.