It should be possible to flash older rom via Odin. i do it all the time on my phone. though never tried on the tab.
I updated my tab this two days back, and i prefer the old notification bar on the bottom. but can leave with the changes there. didn't find any other issues other then my home screens were reset to default.
Give me some MB's http://db.tt/IzxPvtOl
Samsung galaxy S3 GT-I9300 Running Stock Jelly Bean 4.1.2