Downside

The only way they could make it work is if you the rewards you got were NOT game changing, custom camo paint or being able to choose what your player looks like.

The game would be completely new player unfriendly if those who could play 7+ hours a day had an advantage over those who could only play a few nights a week and at weekends. Why should I have to give up my job/social life etc just to compete on level terms. I'm all in favour of giving rewards for those who put the effort in as long as it doesn't affect those who just don't have the time to spare. It wouldn't bother me if some guy was running around fancy camo and a funny looking soldier as long as were evenly matched in load out.
Afterall surely those who play longer get the advantage of knowing the game better so should have an advantage in skill and game knowledge anyway, if not well then thats their problem and know amount of special unlocks will change that.

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