I’ve been reading the excellent Basic Fantasy RPG (BFRPG) rules lately, one of the thing I really like about that system is the lack of level limits for the non-human races. They always seemed so arbitrary, as much as I understood the rationale for them in OD&D, which was that the campaign world was human-centric, and allowing demi-humans to advance without restriction would change that balance, given their racial abilities. Of course B/X has race-as-class, which is another way to dispense with level limits, but I prefer players to have more choice when it comes to class. To allow that choice, but still preserve some of the balance present with limits, I am just adopting the BFRPG rule that humans and only humans get a 10% bonus to earned XP. I am also keeping the S&W Whitebox wisdom bonus – +5% to XP for any human with a wisdom of 15+ (this is cumulative with the 10%). This has the advantage of simplifying things a bit at character creation, since there are no more point swaps for prime requisite abilities. Want to be a Dwarven cleric? Sure, no problem, you’ll just advance a bit more slowly than a human cleric. Of course, many campaigns never even run into level limits, as much as players like to complain about them, still the added 10-15% bonus from the start is an immediate incentive for a player to run a human PC. I updated my house rules for S&W Whitebox to accommodate this, and am also using this rule in my current OD&D campaign.