Unfortunately, a wipe is needed to downgrade, but it is not very hard I did this also. I found that the CM11 GPS always-on bug makes it currently unusable.
Download Koush's Helium from the Play Store.
Make sure root is enabled (I believe it is on by default with the FXP builds, but if Helium complains then it is in the CM11 developer options).
Use Helium to make a full data-only backup of all apps an external SD Card (If you don't have one, go buy a microSD for $10 its nice to save your pictures/videos to anyhow).
Save a copy of the FXP302 CM10.2 zip as well as the 10.2 Gapps (
http://goo.im/gapps/gapps-jb-20130813-signed.zip ) onto the SD Card.
Boot to recovery, wipe system partition, Install the CM10.2 zip file. Install the 10.2 Gapps. Reboot.
Retype your google password and your Cyanogenmod password. Install Helium from play store. The rest of the Playstore Apps should start automagically downloading too. Use Helium to restore all your data from SD card -- it will prompt you to download any missing app you need again.
You will probably have to re-setup your home screen. CM11 defaults to Launcher3, while CM10.x uses Trebuchet