I think that power armor would bring more fallout into fonline
so i support this idea. Few things you forgot about PA: animations of player wearing PA are larger, so they are even larger and easier targets for aiming cursors. Also player wearing PA will be n. 1 target, just on principle, it is more prestige target.
I would not like see PA in game as an another stock item. PA should be very rare, rather team (faction) item than an armor for every solo players. How? PA could be founded in special encouters, but it would need a lot of specil skills and items to repair and maintain it. It should consume MFC, to recharge it, you should have a very high science skill (200 and more), also repair would need high repair skill and items, mostly not craftable, that would not drop from every town or glow chest, but would be very rare to find in wasteland, so it could encourage player vs. player trade.
So in fact, whole PA should not represent item that make overpowered chars, but it should be more like sign, that shows others that you represent high game social cast, because you need a lot of time to afford and maintain this item.