IS it possible? (insert super long kirby message that tells you how too do it but he is too busy too do it himself!)

no.

yes.

How's?

The answer is no.

Or is it?

Only if you have it randomly change upon spawn.

No.

Yea, I've seen that. Anything like that SP map that let you choose your armour?

You could have a dressing room in a map that has pictures of armor pieces next to a changing booth. When the player enters the booth there is a trigger volume (or a button device) in there and through scripts detecting who went through a booth then the booth with change your armor permutation to that picture. This is not restricted to full armor sets either. Want a shoulder from one armor set but helmet from another? sure! Want your player's voice to change depending on what helmet you are wearing? sure! Just set up the gbxmodel/biped up yourself! This, as I see it, is completely possible.

Now this would be downright ridiculous in a multiplayer map. Waste your team's time. But if there is a way to save the armor permutation so that you spawn with it every time then you would only waste your team's time once.

A UI button to change armor may also be possible.
http://hce.halomaps.org/index.cfm?fid=5542
This SP map has an option to change armor when you go to the pause menu.
I have no idea how UI/Button stuff works. Not sure if player specific UI/button stuff syncs in MP.

To my knowledge, collision models can also have permutations with different materials, so you could have a shield gauntlet or more resistances to explosives while others can have a suicide vest on that explodes when you die. I would try this stuff out but I don't need it yet and My scripting skills should be good enough to do stuff like this. I think.

So overall
Yes, you can do it. Now I haven't actually done any of these but they don't look impossible at all.

Don't private message me about this.

You actually can make it so you can use preset armor changes via a UI widget or use an item that would change the permutation if you're holding it. OpsY did the latter for RPG Beta 7, and I saw somebody do it on some xfire video which I cant recall where is at this point in time. I have the script OpsY used but as spral kind of said, it wastes your team's time. the UI method would save it for every time you spawn but the object method would essentially drop every time you die.

Yes

There is a script that allows you to change permutations on a biped. So in theory, yes. It'd just be too much work to set up.