Just to make sure I understand. "Both receivers" are used for all channels except 16 or 17 .. the CB picks the primary or secondary .. but 16 and 17 can only be fed by the RX they are connected to, right? So in the (admittedly unlikely) scenario that one of the RXs has no signal (e.g. one might be 2.4 and one might be 900, and there is some interference on 2.4), and that's the one with channels 16 and 17 .. then there would be no signal for 16 and 17.
Is this correct or not??
Maybe some Jeti magic I don't know?