I wrote it somewhere else, but this is a good place to repeat it.
The XP genereating places are broken, especially so after L39.
I had heroes there with NO Area Lore. They gained levels every 6-7 turns. After L39 the whole thing went haywire. For level 39 you need (forgive me the exact number) some 130,000 XP. For L40 you need 4,900,000 XP. Now, granted, it matters not IF XP gain is scaled (but then again, why have such a weird high level requirement) and this gives the XP generating place a huge benefit: battle XP is not scaled to the level of the hero (or so I think. Linda?) so the hero sitting on his haunches goes way faster than the hero risking life and limb on the battlefield.
It got worse: I went from L43 to L63 in one year (!)
While we are at levelling: at a certain point gaining levels is moot - you cannot spend more skillpoints. So, juyst have a level cap instead? or maybe have higher requirements for the higher level skills:
L1 Curse of shadows - costs 1 skillpoint.
L2 Curse of Shadows - costs 2 skillpoints
L3 Curse of Shadows - costs 4 skillpoints
L4 Curse of Shadows - costs 8 skillpoints
What you can see there is that it becomes harder and harder to max out every skill - making heroes more specialists in stead of jack-of-all-trades-and-master-of-all-too
I strongly suggest a level cap for the XP generating places. L3-5 for units, L10-15 for heroes: that way you can 'force' players to seek out actual experience in battle or adventure.