I guess I was curious because FC's own narrative mechanics use XP values as a sort of building block for encounters and other adventure benchmarks. I wondered if anyone who uses this or any alternate experience system has a problem making it work.
The "XP values" for monsters and opponents is also just a measure of how strong any particular mob is in relation. Same thing with traps, and benchmarks.
In my games, I used a mixture. I used some XP gains, but whenever I wanted to level I would just go.... "And you get a bonus of X so you level." and handwave the rest. Though, I'm currently playing in a handful of games that aren't using XP at all (not FC mind you), but level you whenever the GM feels like it. It would work just fine with FC as well, and would get rid of the players seeking XP, rather than adventures.