Another Medicine Operative here, and I can't say that I had the same results at all, regarding Kaliyo's toughness vs. Vector's. Kaliyo not only generally keeps mobs on her more consistently, I find healing her far less strenuous. And I give them both a mixture of blues/greens. Which is disappointing to me, really... I'd much rather have Vector around than Kal (being a -generally- lightside, pro-Empire Operative). But I simply can't solo with anyone else. Kinda wish Lokin's Rak form were a viable melee tank, since we lack one of those.