Now first off let me say I want the create a solider system from ghost but it should be change slightly so you can use any 3 attachments as long as they dont use the same buttons. This idea will just add more in depth customization.
The idea is simple, if my idea would be implemented it work like this: everything in the game would work with it; by trading certain attributes you can make others better
So like for a player with an LMG you could trade health to make your character move faster.
for a weapon give up some bullets in a magazine and slower RPM for higher damage.
Trade off the number of dogs you get with attack dogs to make each dog harder to kill and stay active longer.
Of course there would be rules and limitations to the system like as damage goes up RPM goes down or an automatic weapon cant have higher damage then 50.
Note that you cant make damage and RPM better at the same time but say you wanted to trade slower RPM and lower damage for better range and lower recoil you could do that.
Attachemnts wouldnt be affected by this positively for example you couldnt make an SMG shoot slow and have 50 damage upclose then use rapid fire. Doing something like that would revert the weapon back to original stats.
You can't remove attachment penalties so say you throw on a silincer you cant use this system to cancel the range penalty, but instead of lowering range you could make it lower damage.
Another limitation would be a players/weapons/killstreaks would all be separate. So you can't give up some weapons stats and killstreaks to give your extra health.
So you cant give up your player health to make a gun with 1000 RPM that kills in 1 shot to a player any where on the body at all range with no recoil.
If balanced properly and the limitations are set right I think this would be a great system for a cod game to implement as it would allow players to better customize weapon for specific game type and modes and fine tune weapons to your play style.