Just posing the question, how would we separate this forums "advanced" modellers, from our "intermediate"?  I think it might be difficult to work out. Maybe more categories might help. Maybe those with past wins are automatically forced in to a higher difficulty. If the contest is structured this way, and placing your entry in the correct skill level catagory is left to the entrant, then you run the risk of the dishonest behavior Norm mentioned. Left up to the admins, it's an extra burden of rules, policing and tracking. with more entries, it might get onerous.