Thanks for the replies!
I am really struggling at this point to find space for all the good characters I have or am building. I am currently running Barriss, Lumi, Dooku, Sidious and Asajj, all of whom are good and play specific roles. I dropped Chewie a while back when I got Sidious. Lumi and Sidious are both going to be 7* soon and have "safe jobs".. the other three I am on the fence on.
I really like having two healers and am not sure I want to replace one of them with a tank who dies, but it is possible that with a lot more offense via Expose etc I can do without Barriss. Asajj I know is not super popular but I've gotten very good at using her, usually getting more than one AoE off per match, and she also stuns and removes taunts. Poe sounds cool but I am not sure if I can make good use of him.
I am also unlocking Kylo, and every time I have faced him he has been super nasty, so he may be hard to resist using.
Meanwhile I have Boba, he is good but has not earned a spot in my top 5. He's been very helpful in dark side missions. I don't think at this point I am going to star him up further, he's good but just too slow and doesn't bring enough to the table.