I don't think that the characters really become more powerful in the adventurer kind of way. Or even in the supernatural tv serial kind of way. 
Also, I don't have a particular genre. More of a feel and smattering of texts as sources. 
The stories I think of challenge and reveal various ideas, emotional state and shake up the status quo. This happens in AW often and doesn't need to be a function of advancement. 
Maybe there's not XP per se. There's a bit in AW where Vx talks about sometimes the characters spend advances and other times they get an advance by working for it in the fiction. Hmm. That could work.