Warning: This seems to interfere with root (permissions?), you will most likely need to re-root. pretty much painless took me approx. 1 minute. Worth it.
ALSO: I did a complete uninstall/removal of Xposed before this, just in case.. and would highly recommend everyone do the same.
So I managed to de-odex /system/framework, system/app and /preload/symlink/system/app.
I used dsixda's kitchen, it automatically knew we had more apk's in hidden.img
with JellyBean Samsung has moved some .apk's to /preload/symlink/system/app and left a symbolic link in /system/app, likely to save space on /system.
Flash in CWM recovery that is compatible with jellybean.( 220.127.116.11)
This update.zip will wipe your /cache and /data/dalvik-cache and /preload/symlink/system/app's automagically.
Keep calm as it is extracting and be patient on reboot and enjoy...
Oh and it is true stock, nothing removed so file size is beefy at 402MB.
Try to go easy on my hosting sites so they don't get suspended, I may host it at another if I need to.
Should anything go wrong, simply advanced restore /system only.