Honestly, I think score is a better system than the multiplier or the proposed system in this thread, but obviously the score system needs more work. It needs to give points to anyone around a ranged character that does damage (like a shielder or pikeman protecting a group of archers). It needs to give more focus on killing blows for battle, because that's what matters most. Siege needs point possibilitis added for things specific to that game mode, like breaking/damaging doors, capturing the flag, etc.
If you want skill to define the experience and or gold gained, then you need a system that accurately represents skill, and while score is alright, it can be much better with just a few improvements.