As a player, enjoy the challenge of developing a character from first level. Therefore the basic precepts of the CORE boards are what made me pick CORE over the other RPG boards:
Everyone starts the same level.
Everyone starts with the same skill points.
Everyone starts with the same starting gold.
Everyone plays by the same set of rules.
There are multiple DMs so the world doesnt depend on a single DM.

My Vote: Dont change Greyhawks starting level.


That said, there are people and DM who enjoy the challenge of playing higher level characters. A separate board is one solution. Keep the same precepts, but change the starting values of each. The down side would be that it may drain players and DMs from Greyhawk board.

Another option would be to create an area where character level is inflated. All characters adventuring in this area are X levels higher when they enter and X levels lower when they leave. Experience would be rewarded as if they and the foes were X levels lower. There inflated level would always be X plus their base level. Items and treasure would have to be adjusted upon entering and leaving as well (ex: normal +1 sword = inflated +3 sword?). It would require a lot of work on the GM to insure no inflated items or rewards made there way into normal Greyhawk.