hey all, throwing in two cents on this topic..
but, to me, adding power armor units to the game would not unbalence it, if you had the right control over its use.
for example, "omg, he's going to pwn us all with his uber PA! F*** this!" common thought in the minds of many who would be in other factions.
but, things to remember about the nature of the brotherhood of steel.
first they would not allow their tools of war to be used in random murdering, so the number of people that this mighty suit of armor could be used against would be very very small.
and the people who it would be allowed to be used against would be he worst of the worst of the waste landers who would some how threaten the brother hood of steel, which would only be the case if they stuck their noises in to the brotherhoods business, which would probally be them trying to steal the power armor.
second, if some one did some how steal the item, well i don't see why they couldnt enjoy it.. but the thing being, the brother hood should get the power to have its members have dection devices that could see it if it was stashed in some ones tent, so if some one stashed it they would leave their tent open to be looted by every BoS member around that could happen to be roaming around that area looking for it or not.
third, if, and i mean if, some one was able to get a suit, you would have to have a almost perfect record to be able to use it, which means, no shooting people, no raiding towns or bombing NCR or tax road blocking towns that don't have guards everywhere.
which basicly takes out all the fun things you can do if you like to bring suffering and death to your fellow waste landers, so you basicly would have to follow the brother hoods rules if you want the armor, which, to be blunt, they're all a bunch off hard arses.. so you won't get away with abusing it, unlike the raiders, which one of you suggested giving a 10 guss rifles to which could be used by anyone, you also have to remember that the BoS has no real reason to attack the raiders unless they attack them first.
so, in short.
1: you would be signing up to play a almost purely defensive role, with limited quests to find more tech to loot.
2: you would have to be gifted with enough self control to keep your dirty hands off the devils daughter to be able to get one in the first place.
3: you would not be able to do much with it, due to the fact that it would not work to take it apart, nor would it work to give it to another char due to the fact that it would be like placing a hell of a bounty on your own character.
4: it would no un-balence other factions due to the fact you should not be using it against them in the first place if you want to keep it.
5: it would not make people swarm the BoS due to the fact that they will learn pretty quickly that they cant use it for much even if they do get it, and even if they do get it they will have to be good little boys and girls and use it like they're told to by GMs, and perhaps higher ranking players..
6: as for who should be able to fix it, well you could add a req for a machine only found in the BoS main bunker that can help you hold it all up to fix it, or just allow anyone to fix it, but only a BoS member would have a chance of keeping it in good shape and keeping it at all.
7: also, if the "you can find it along with some one elses tent and all his goodies" thing doesnt stop people from stealing them, always remember that the BoS could place a bounty on a person like that that has one, not to mention no faction would want him to be in their as it would show their faction base to BoS members as well if he was stashing it there, and could even draw the anger of the BoS (which would be one of the few times they could use their other suits of armor) upon them, making them a target for a deadly force with power armor if one of their members had a stolen suit.
8: last but not least, if you make it so that only BoS members could fix the suits than if a player stashed one he could only use it for so long before it broke, meaning that he would have to get rid of it, which would than open up a slot for some one else in the BoS to get a suit and than every one would get on with life, not to mention if you used it to camp areas for easy player kills to often word would get around and others would want it, and so on and so on.
these are my suggestions based upon what others have said, hope you kept reading untill the end heh.
cheers all.
-Ulrek-