Default Switching ROM

Hi guys,

Just want to know what do I have to do if wanna try the CM m1 (waiting for features on Omni) and after return to Omni.

It is sufficient a factory reset + flashing the ROM or I've to flash also other stuff? (like standard kernel or something...?).
Thanks and sorry for the noob question.

-Tapatalked with Nexus5-
- SlimBean + AK kernel on Nexus 4.
- OmniROM + faux kernel on Nexus 5.