People are getign Random results because you are failing to take into account Aggro Adjustting skills do not work on this bos with regards to the first Bite.
So if you ToT & MD someone on YOUR Omen they will be high threat but on the bosses aggro table that aggro will showon the person who gave it over. So it stays on the Rogue or Hunter.
ALSO. Mirrors work the same and dont devide you aggro it will stays on the mage for the purpose of bite.
Factor this into your attempts and you can control who gets bitten easier.
We just start the fight with a 5 sec no damage rule for anyone who isnt a Tank or the biten person. With a solid bite order its cake but we do it that way so the person being bitten doesnt have to wastre the CDs to get top aggro and can pop there CDs as soon as they are bitted for maximum output.
But if you pp your CDs nothing at all can stop a mage being bitten. No class can generate as much single target Threat as a mage for the first 20-30 seconds of the fight.