Um, no. The health steal part is already there. The zeta addition ONLY affects him and Krennic when together.
Edit: Wow, completely misread your question.
Absolutely! I run DT in arena without Krennic, as I'm still finishing his gear and last star. DT has a great kit and goes very well with troopers, deathmark will never go out of style, doubletap stun on rebels is great in TB, and an AoE buff remover is clutch.
Granted, my eventual plan is to gear up Stark to take DT's spot in trooper lineup so he can go hang with Krennic on another squad.