I'd say boarding party first boss is difficult. It requires a lot of movement, isnt it? Also false emp 2nd boss will require some movement, but rather easy to do that. D7 last boss also has a lot of movement, I'd say.
I finished BT HC today with 3 fresh lvl 50 DD sorcs who have a few points in healing tree. For the last boss I'd recommend to not tank her close to the slaves. Because when she pulls the slaves and if they are very close their casts are not interrupted and strafing wont work