The only way you will benefit from a class 10 card is if you do photography in raw format with a requirement for rapid snapshots or 1080p video recording in a higher quality. You'd be better off saving the money by getting a good quality class 6, or even a class 4.
I'm using a Kingston Class 4 32gb card without many issues. I did have a weird issue with the 720p recording at one time, but I haven't tested with CM yet to see if it was possibly a software glitch.
HTC Incredible 2
CyanogenMod - Nightlies