As of right now, radio transitions will begin to stack up (at least to a certain point). I have heard the proof before on either range or vox (can't remember which). What I heard was radio banter "Get the troops in, get the troops in!" up to a minute after the base had been taken.
As for the second part, I disagree with you. My squad is very... dysfunctional. We rarely say anything constructive in the way of wining on VOX, all tactical communication is done over range instead unless we are all in the tower. The only time we use the VOX on missions is if we split up into smaller groups and spread out, but even then range is still used for the majority of tactical command.
