@Bissig: I call your team-within-the-team a fireteam. Some people call it a squad, or a unit (I said "unit"). I'm saying that instead of having a bindkey for chat to my fireteam/squad/unit/Team Gold, I would just type as normal, and chat would be squad-only, unless or until I press Y or T. I would use Gold, Black and Green, for Attack, Support (Attack B/Defend) & Build, respectively, instead of your suggestion, since Blue and Red represent the Human and Alien teams in toto. Fireteam-only chat would be in red, possibly centered, or echoed and centered.
Fireteam=Squad=Unit=Attack/Support/Build Sub-Components of a Tremulous "Team"
Also, since I don't think the OP should waste too much time arguing with naysayers, I'll just point out that the reaction of +OPTIMUS+, for one, will be fairly typical. It seems to encapsulate several key questions: how will this work, over the course of a match, as better players or known friends or disguised griefers enter and leave the server; how will it work at various populations and how will it handle the wide swings in server population that can occur over an hour-long match; what server size do you envision optimizing play for; and of course: Can you see the potential for both abuse and false cries of abuse, at yet another level within the Tremulous community that this would create? Lastly, many players feel that you should follow people worthy of following, not someone somebody else voted for, and that natual leaders assert themselves naturally, and take charge of the situation, and are "promoted by the battlefield itself", so to speak.
That said, I repeat my earlier imprecation to googles that you simply make the thing and prove me/us/them wrong, and I wish you godspeed and good luck in this endeavor. What do you think of the two leader (attack leader & base leader) idea? How about Bissig's three squad chat idea? You could have players join the attack team who voted for the attack leader and want to follow him and submit to his commands (who would be disciplined with probation and slap) and the players who want to follow the base leader and submit to his authority (denybuild and designate), plus a third squad of the freethinkers, the feeders, the bleeders, the ronin, the leaderless, the first-to-be-kicked.
Blue=Human
Red=Alien
within each team:
Fireteam Gold = Attack Unit, led by Attack Leader
Fireteam Black = The Freebooters, unaligned players, those who will not submit
Fireteam Green = Builders & Defenders (OK, the campers and probationary feeders), led by Base Leader
Anybody the Attack Leader puts on probation, the Base Leader tries to teach to defend, to join a rush group, to teach to build, to show him how to help with moves, and how to leave base without feeding. One dude takes the players who want to rush together out to rush. The other dude takes the n00bs under his wing and tries to move, build and defend. And a bunch of players listen to neither guy.
Oh, when does the initial vote happen? How many votecalls per round? What happens when Anger/Dracone/TinMan/n00b pl0x shows up and I want him to be my leader now? You can substitute clanmate/brother/best friend/superkiller/master builder, but you know what I mean.
Sorry, I meant to keep that brief.
Please make this thing, if you can and will, sir.