D&D 4e loves its experience pools in encounter building, and, because it is a system that inherently cares about party balance, carefully has laid out the math for experience - to encounter level -to advancement ratios. But my game group has done something entirely different.
My GM has simplified the experience system to this: Every 10 xp a character levels up. XP is awarded based on relative strength of the encounter to strength of the character. Example: Player A's lvl 14 ranger, B's lvl 8 cleric, C's lvl 10 battlemind and D's lvl 12 mage all get into a EL 12 fight and succeed. A would be lucky to receive 1 xp point. D would probably get 1. C would most likely get 2, and B would receive 3 points.
(While not pertinent, he also rewards bonus xp points for completing missions and good role playing.)
I'm thinking of adapting this system to a 4e campaign that I am going to run, but am wondering how this type of radical shift in the advancement system will affect encounter-building, or if I should be worried that my players won't advance fast enough, or more likely will advance too quickly.