To me the game, maps and weapons have been developed to create an overall balanced game, that's probably why which ever team you join you have the same choice of weapons/perks, if the weapons had been coded to accurately mirror their real life counterparts and, you could only choose the weapons/perks that relate to the team you join then it would be unbalanced in favour of Marines/SAS.
Take the .50 cal sniper rifle as one example, you can take a hit (if not hardcore) and still live and run for cover, if it reflected real life then even a small hit would take you out, in essence if you, by any means try to unbalance the intended gameplay other than the intended by the devs it's exploiting in my opinion.
You have to ask yourself why am i buying a mouse out of hundreds for sale that changes they way a weapon fires, is it to gain an advantage over a player who uses the weapon as intended by the devs.
If it were possible and there was a piece of hardware out there mouse or other, that increased the killing radius of a nade by three or four times or removed all recoil would you be saying, "ah well it's just hardware and not exploiting" I doubt it very much.