Honestly, if it was as the OP suggested, only for fun if my friends and FC wanted to run it. Otherwise I wouldn't bother.

Being a max level Omnicrafter who does the Hunt, I don't have any need for Expert Roulette. I have tomes by the thousands, decent gear, enough gil to buy all the minions and music. Even dungeon gear with 5 slots has no use to me. Materia is poured out in hundreds from Eureka too.

Something unique would get my interest though. For example a rare mount or exclusive shiny glamour for completing every "Challenge" dungeon.