No one could accuse the team at Cyanogen of rushing anything to market. Six months after KitKat debuted, the CyanogenMod team is still perfecting its modified release for dozens of devices. The sixth snapshot or "M" build is rolling out on the buildbox right now. Custom ROM fanatics, you know what to do.
"M" builds are generally more stable than nightly builds, but still not good enough to make it to Release Candidate status.