Ran the Bridgestone Battlecross x10 this weekend at ClubMx. Conditions were a mixture of soft but packed red clay, soft and ripped deep red clay, and sand.
Back tire is awesome. It seemed to have similar grip to the x31 on the packed dirt and just had tons of traction in the sloppy stuff and in the sand. I think I might be running this tire all fall and winter here in the Carolinas, then go back to the x31 rear when it starts getting hot again.
Front tire was okay. The knobs are really skinny and soft and made the front end feel heavy and somewhat wallowy on packed dirt, but I guess that's a good thing in sand. Initially I didn't like it all that much but thought it performed well in the really loose stuff with a lot of tradeoff on packed dirt. I may want to try the x31 front with the x10 rear.