Can someone go into recovery and hit backup, then tell me if they have the option to backup efs file (data, system and such will already be checked) you won't create a backup just by doing this.
If your installing a new ROM
Wipe cache, dalvik, and do a factory reset.
If your flashing another nightly, same ROM wipe cache and dalvik then flash.
TWRP will work with any ROM at this point.
Sent from my Galaxy Nexus using Tapatalk 2