Power mode eliminates all sway when aiming any weapon in singleplayer. I know that it does not do the same for most weapons in multiplayer, but is this the case for snipers? I could check, but I'm not buying Crysis 2 for PC until a patch comes out, and my PS3 is more than arm's length away from my current location. I would assume though...?
If so, that should be enough for power mode. Your idea would not create an unbalance though, snipers are currently at a disadvantage with the small maps and poor hit-detection.