Using nightsister zombie properly

It's definitely worth pushing zombie to g12. Because the 2 proxy deaths NS now get cause zombie to lose all protection, usually long before its lost from damage, she benefits far more from really high health and armor than from protection. At g12, zombie has both a medpack and furnace available, adding over 12k base health, and also allows the use of 6e health mods. With both g12 pieces and a couple 6* mods, you can boost her max health to 50k+, which will drastically improve her ability to survive multiple hits each revive. This is essential to keep those -50% speed stacks off of her which turn her into a glorified statue.
Her max health also affects the new part of her kit that heals other NS allies, and under AV lead this extra healing will let them heal back to 100% health more often to get the 50% bonus TM when they next drop below 100% health.