But what you are talking about is at the application layer, at the RF layer there is still interference and channel overlap. Digital doesn't mean squat if you can't get the signal because something else is stepping on your signal.
RF is RF... its carrying the data, analog or digital... I'm just curious as to what would happen if I took a CB, pointed it at the digital signal transmitter and keyed the mic, how that might or might not interfere. If one RF signal is stepping on the other, how might it affect packet loss (and thereby actual speed) if its being stepped on.