The iC Electret element is a condenser mic, and requires power from the radio. As far as I know, only Elecraft and Icom radios are designed to do that, so you'd want the Dynamic element. Remember to budget for the correct adaptor and some sort of PTT switch - I personally prefer a footswitch to keep my hands free for logging.

How do you persuade that many people to get involved? How big is your club? My club has about 150 on the roster, and only eight people have expressed an interest in Field Day.