The only sure fire way to get updates without any risk is to be completely on stock firmware that your phone came with out of the box or updated officially via Kies or Over The Air (OTA). Eventually you'll get 4.3. At the present time it is a bit like Russian roulette using PC Odin to flash. While obtaining root has been successfully cracked and won't trip Knox users are reporting tripping it afterwards flashing different ROMs. At the moment I haven't with two different devices, both Knox enabled and both running completely stock firmware (see my signature). One of them has to go before Christmas. As of now either can be sold as used but in perfect condition, I trip Knox on either and I can only sell it as used with Knox tripped, no ongoing warranty and partially "broken". So unless a complete solution to tripping the Knox flag arrives (and the devs are getting there) I shall hold off.