I have OB with 6xheal bonus set with a speed arrow and proteccion triangle/cross with as much speed secondaies as i could trow on him... Since he is my only tank and his mind trick gives TM to all from every resisted effect this lack on potency dont hurt me a lot... Cuz if it get resisted by a key enemy toon it usually gives either R2, zolo, luke or ezra enough TM to stop that toon anyway (Stun from R2/luke or TM removal from zolo/luke, or ezra making someone asist).
I dont have any of OB Zs but i find him a very good tank, and combined with R2 smokescreen my OB is usually enough to keep alive most of my dps time enough to kill enemy hard hitters.