RE: Switch harness as a ignition switch.
On electronic ignition it will work fine as most electronic ignitions are set up that way. If it would not hold up to vibration, it would be useless for the radio as well. I use a radio switch harness on all my C&H equipped motors and never had a problem. Just remember that on electronic ignition, you supply battery power to run, not ground the coil to kill. (continuity to run, open to kill)