The way I see it, both systems have single points of failure that can screw up your retract system, however, the mechanical system can be serviced with a single component change at the field and you're up and going again. The electronic systems usually require replacement of the entire unit. So you are either down or need a complete spare. The mechanical system gets my vote. Plus most of the higher end transmitters now have programming features to do all your sequencing thru your radio - if you have the extra channels.

PaulD