It sais i need OS Mavericks 10.9 to play the game

. Is an update to 10.9 better then my current 10.6.8? I heard 10.9 runs programs etc worse because it takes up too much ram. Currently i use the gamers gate version and use Paul the Talls wrapper port. But i would like too see if the native mac version works better? Any ideas what i should do? Does it work better? anyone knows? Updating from 10.6.8 to 10.9 does that meen i will lose anything on my HD? Please help me with this since i dont know what steps i should take concerning this.