If you want true customization instead of a scenario where every player chooses pretty much the same edges because they're obviously the most powerful, then there would need to be some serious rejiggering of edge costs.

I agree that imm exp is hard to come by. I'm led to believe that the amount of EP you can get from role exp caps out pretty quick. Could be wrong. Beyond the initial entry and maybe one or two more, I don't get the feeling that attempting to farm EP via role entries is very effective.

If the goal for edges is to ensure that every character of type X I meet is going to be a little bit different, then we'd want to have as a goal that every edge PK-relevant edge is taking approximately as often as every other PK-relevant edge. Achieving that would require making some edges more expensive and other edges less expensive, and would require constant adjustment in reaction to the player base's shifting preferences.

If every assassin starts taking edge X then edge X needs to become more expensive and/or everything else needs to get less expensive.