Big O is one of most tame and least volatile of the circus games. Craziest version of Omaha I played at SQM earlier this year was Maximum Omaha Hi/Lo -- the number of hole cards was determined by the number of players at the table. Five-handed, each player received 8 cards, retained for the duration of the hand. Non-nut flushes and lesser made hands were pretty much worthless, and players who didn't grasp that made it pretty profitable.
Super-Hold'em is a similar evil, hidden holdings game. Possible to have flushes with only two suited board cards, and full-houses and quads are both possible with no paired board. Nut flushes are often losers. Two-pair, sets, trips, and even nut straights are rarely good.