As boy who studies on high school I wanna get the helicopter and drive on it.
At first I didn't like the thether turret idea, but it is kinda growing on me. Kudos to bringing the idea to this thread.
How about a deployable pod that has to be placed within a radius of the base, let's say for "energy needs". The pod could cresent open, and two beams that are like "energy ammo chains" lock onto the players arms Then the Legionaire can move while tethered to his new source of ammo. It could maybe give him a little shield boost. It would still be up to the player to aim, but he will now have the added benifit of the extra ammo and shielding boost. What the turret can then shoot would be dependent on the SUIT tethered to it, light, medium, or heavy.
It would then be a strategic practicing point for the teams to learn the best placements for the little dome turret tethers. After all they would be fixed points, and highly vulnerable to sniping. You could introduce an "ELF or EMP Missile to counter these points as well. As far as animations goe, just let em BLOW UP into a million pieces like a Legionnaire.
You could solve the "whole Tether" equation by simply allowing a deployable TURRET that the player can sit in. Like a 360 degree ball seat housing he has to sit in with a gun attached. The player could rotate within the ball and aim, receiving the added cover of the seat's "cage". They would be dependent on base energy as all things are in this game type, dependent on recharge or ammo. The animation for placing it could be some sort of case or ball that is placed down that either grows into the turret, or even teleports the whole housing to the spot of the placement.
The old Tribes based static "Ion Turrets" were honestly a LAUGHABLE threat to good cappers with established ski and cap route. The little ai monkey in the turret would go "pew pew pew" and a flag runner at speed could just zip through them because the turret rotates and moved so slowly, and the capper could enjoy the fireworks as he sailed by. They became fun harassment when base defenders could block or slow a guy down for the turret to be able to get a bead on them. They also became more accurate within a "sensor array". Sensors were vital for your turrets to be effective.
Also for the negative Nancy replies here,

there is still no reason where "Deployables and Vehicles" were not allowed on some server set ups, or make it a vote option. That way they can have their more traditionally "vanilla" game of Legions to play with when they want, and the rest of the boys get the new toys.

(And hot gamer chicks too)