I do think Arcadia Quest would make for a good Competitive game played in a tournament. I think there would need to be a few rule tweaks like to make it playable in a tourney format.
*May choose your party instead of random: So people can show up with the party they wish to use. As long as it is equal to all and not random.
-Might have to have some heroes labeled as epic so one epic hero per guild.
-Might say 'core 12 heroes only' tourney
-Might allow any hero and recommend proxies for Exclusives should people not have them
*Missions could either be laid out before hand or random. Either everyone knows every mission beforehand, or everyone plays the same mission and it is randomized on the spot for everyone in the Tourney
-Might say: This tourney will be 6 games, these are the 6 missions. This means everyone plays the same mission and can plan for them.
-Might say: This tourney will be 6 games, Missions will be chosen at random at the beginning of every round. Everyone plays the same mission in the entire tourney.
-Might say: Person with the lowest rank at a table may choose the next mission.
-Might say: Every table will randomize mission
*Loot buying, I think you would have to basically give people full access to the loot opposed to the randomness, especially if people were to change tables every game. Basically remove dupes and say 'you may buy from these cards' after every game.
-Might say: Here is the shopping list for everyone between missions and people can buy what they want
-Might try to keep the randomized notion per-table
*Attach 'battle points' so every game objective, tables re-seed based upon success. This will allow players who are 'on top' to slowly head towards the top tables and those who fall behind to be placed with other people of similar gear progression.
Examples:
1 Gold = 1 battle point
Completing a quest is 10 battle points
Completing a PVP quest is 5 battle points
Then the next game, you re-rank everyone based upon battle points, and re-assign them to tables. So if you got no quests and 3 gold game 1, you will probably be with other people who had a bad game.
This is basically how '1-day bloodbowl tourneys' kinda work and they are a lot of fun. The trick is having enough people bring their materials since usually Bloodbowl only requires a PITCH and people bring all their own models and such they need. Basically there would need to basically be a full-set per table. I could see maybe 'tourney mats' being made which has the board layout, the quests and monster components all on a single poster sheet so you wouldn't need to arrange tiles and stuff every game. If the board was a laminated poster, you just lie it out and put the tokens on top and away you go. CMoN could even produce 2-sided 'game posters' for mass tourney play where you just throw down the poster and game is ready to go.