I agree with Fanest, level cap should be reach when you've done everything in the game (or almost).
That does make the idea of enemies giving out a variable amount of XP based on your level seem like a reasonable idea.
I would prefer a fixed amount by type of enemy (and the same amount for each member of the team that fight). The exploration bases mean (to me) that it's the player who should find a challenge. The game should'nt be adapted to the level of characters : You win against a great enemy you'll have a great amount of XP, you win against a lower you'll have a lower amount of XP. That's all. The difficulty in setting this, is for the developpers (ouch). Or maybe, I misunderstood everything *whistle*
