We tried some electronic ones (and prob not this make -its about 5 years back now) we were given to try at a show for the three days we were there and while at first it seemed a good idea after a few peeps had pushed buttons it all went tits up and it was hit or miss whether it stopped the motor or not. I'll stick with the curly string..less to go wrong. We also had an incident on a coastguard rib a few years back when the helmsman not using the footstraps got sorta launched out of the seat ( it was b.... rough to be fair) and ended up down on the port side deck, head down legs up!
The kill cord had not pulled out cos his leg was now nearer the control box than it had been so we were still powering on. I reached forward and ripped the cord out (starboard side) to stop the boat which was now doing everything short of handstands!
Cant do that with an electronic gizmo!