Right now the SD team is pouring over XML, trying to find a solution for the Hero leveling problem. I have complete faith in their ability to do so. As such, I will focus my thoughts on the Hero's opportunity to acquire traits. The standard way is to of course level your hero. A selection of mostly common traits and a few rare ones will pop up. There is a good differentiation between mages, defenders, attackers, and assassins. These are all rare finds and give big bonuses. They progress to give the player specific traits in one of those fields, but you can take all paths and most do by level 15 or so. I believe it to be impossible to have one trait block another, though that would be a preferable balance mechanic. (It is actually a big part of the problem with overpowered heroes.) The other way to solve this would be to give more incentive to go down the path you have already chosen than to pick all the path traits you come across. Once again we must go back to the bible of RPG's, D&D.
Crossing classes was alot of fun, but you don't do it without a plan and there are some serious consequences. I am not saying we need to go into the extreme detail of D&D, lord knows that even their MMO couldn't come close to getting things right. I am saying that there needs to be a spell or a buff or a bonus down the trait tree that makes the human player avoid getting the assassin, defender, warrior paths simply because they are the best traits.
We have a chance here to turn these heroes into classes. How you ask? What is to be done you ask? Now, I am certainly no Lenin -he would only care about the economy and city building- but I can say that the paramount task is to expand upon this basic class system. There needs to a Healer, a Wizard, a Mage, a Fighter, a Barbarian, a Rogue, and a Noble at the very least. The latter is perhaps the most exciting addition Elemental makes to the genre, as there is little need for a Noble class without the strategic level we find in this game. Surely I have taken for granted the developer's need to compact these categories into the incarnations we have already experienced, but it needs to be said that adding only three classes opens up a multitude of possibilities.
Taking on one path might not prevent you from getting one of the others, but the synergy between each trait in that tree should keep you coming back for more. Having levels for some traits, like Evoker. Having traits that work in tandem, like Might (+3 Strength) and Recoil (Half of damage taken is returned to attacker, if Strength is higher than attacker). Having some very rare traits that require a high level. Having some traits that require a few common traits in that path. And finally, traits that are not rare, but require two paths. These would be the cross-class classes, like Battlemage, Assassin, Spellsword, Minstrel and the like.
*This is getting rather complicated, but in a way that most people find fun. Which is why we need a trait tree in the game and on the website.*
The final addition to really perfect traits is to allow quests, technology and unique adventurer buildings to unlock traits. This one is pretty revolutionary, but given the prereq xml I saw, should be easy to implement. Killed a race of giants? You just got the Giantsbane Trait! (+25% attack vs Large opponents) Just slew a dragon? You've earned the Dragonslayer Trait! (-25% damage from fire, piercing)
I hope these ideas are taken into consideration. If it's something you guys decide is not part of your vision, I would be more than willing to make a mod with these factors in mind. Hope it makes it into your list so others can play this way too. 
