Auditorium and OOO's are the same, me thinks. Your'e right, I'm thinking of Jumbo but I still stand by my judgement, OOO or Auditorium sound a hell of a lot better and louder depending on the wood.
Also, dreadnoughts are used commonly for more strumming with some picking whereas the Triple O and Jumbo are for more plucking with some picking, generally.
Also, don't go for makes. Ask the guy's, (or gal's) at the shop to bring you X guitars between £X and £X and then sit there and play with your eyes closed. I did that for my classical and I got an incredibly nice solid Top, Back and Sides Admira, (hand made in Spain) for £200. And it just keeps improving it's sound.