Hi

I've been working on electric retracts for quite some time now. They are in no means "easy to to", especially the wiring is very tochy and also complicated, as a simple "cutoff" will result in jamming. You need to electronically brake the motor the instant it hits the cutoff switch....not easy from the electronics-side.
I now have the prototype rig up and running, and will soon be building the prototype version.
The "ECU" will be about the same size as the JetCat/ProJet/Orbit turbine ECUS, and tests and calculations show that the cylinders will be "pushing" between 30kg and 100kg (66-220lbs). Gear cycle time will be around 2.5 seconds, with the speed being adjustable for each leg.

The complicity and manufacturing expenses involved will probably make the pneumatic setups financially much more attractive than the electric types, those will probably only show up every now and then....my guess.

Best regards
Hank