Am I to understand that Vader's zeta isn't worth it?
If the zeta is your first or second one you are likely to need it in arena to stay competitive in your shard, if its after that you are likely to not need it to solo rancour easily.
You have most of a zader team. Obviously for this to work, you'll have to zeta vader. Then vader, tfp, tarkin, ep, and storm woukd be a good one to start with. You look to be close to having cls. As soon as you have him reasonably geared switch him for storm. That team can solo pretty easily. Eventually switch out ep for thrawn when you get him. That can solo easily and consistently on auto.
Replies
If the zeta is your first or second one you are likely to need it in arena to stay competitive in your shard, if its after that you are likely to not need it to solo rancour easily.