Is a Class 10 MicroSD overkill or is a Class 6 adequate? Possible Duplicate:
  Is the class rating of my MicroSD card relevant?  




I don't see any speed class or × rating markings on the 2GB card that came with my phone. Is a Class 10 card going to be noticeably faster (in apps that use the SD storage) than a Class 6? I know that it's theoretically 40% faster but I'm not sure that my Flipside would even be able to take advantage of the higher speeds.
It is most likely overkill unless you are doing a lot of write/reads to your SD card for some particular reason.  The only reason I've known to buy a faster SD card is for photography, when you want to be able to reduce the time it takes to write photos from the memory buffer to the SD card so you can take more pictures at a higher FPS.