I'd still lke to know why you think duplex is so important.

Try talking to my wife on a semi-duplex cell phone someday and you will
understand.

Given the crowded nature of the airwaves it would probably be BETTER to not
have full-duplex. If folks feel the need to prattle on endlessly let them
use cell or satellite phones... and PAY FOR IT. Stay off the VHF for that.