You can just try to take it as long as you have stock recovery installed (TWRP/CWM/PhilZ will cause a soft-brick situation), but depending on what Xposed modules you use and the changes made it could likely fail.
The safest and best way would be to factory restore the firmware via this: http://forum.xda-developers.com/show....php?t=2448960, then take the OTA to 12B, followed by the OTA to 24A. The whole process is pretty painless, I did it going from an old CarbonROM build to the latest stock KitKat in about an hour and a half or so.
To add, you can re-root with ioroot25 and if you need a recovery for any reason, use AutoRec to install the latest TWRP. You need to jump through a few hoops to install recovery on KK and it does them for you. If you plan on staying on the stock rom, I would leave the stock recovery.