Hmmm... have you considered collaborating with someone or a team that had EC HM on farm?
You can either drop one member of your raid for the caller of such a group just for one raid - you'll probably see and hear their tactics and he/ she may have some thoughts/ observations to provide to you.
Or you could do a 16 man by teaming up with such a group - your group may get a significant morale boost by killing T & Z on 16 man AND for a bonus they'll feel T&Z is so much easier next time they try on 8 man
Also are your sents dumping threat after each dd soak on the tank fight? It may help to have different people watching out for different things to call out to the group as well. For example, when making it to the shields - the shields show up on the minimap at the bottom a bit before you need to move into them. Assign one person from each group to watch and call out where the shield is going to be so their team can start moving in the right direction