As usually, you may do it, but please consider you do it "at your own risk",
even if it doesn't brick your phone
As seen there i'm sure someone here had this problem on a Galaxy Young,
I found a solution when i tought i have an empty userdata.img image (i formatted /data and made a cat /dev/stl11)
I tested if i may repair my broken RFS partition, which was broken by a Online Nandroid Backup (My CWM backups never broke /system)
I renamed userdata.img to system.img, i opened cygwin and made a .tar.md5 package, flashed it, YEAH!,
problem fixed without downloading 100MB of stock ROM package.
After that history, i finally created the "Unbricker" package, which rewrites /system and /data
(not cache, cache cannot be integrated in an Odin package)
I flashed it and re-formatted corectly using CWM /data and /cache, wiped and reinstalled my ROM.
Hope it will help you, the download link for : http://d-h.st/tnu