Haven't seen the episode but, I feel like Jax should stay even with no powers. Him and Stein rarely used Firestorm anyway.
I get the impression that aside from the actor that played Stein wanting out was that Firestorm was a budget strain when he was used.
Could be wrong, but I would think Firestorm would be the most expensive with Atom and his shrinking/power suit a close second.
Also....I wonder if Jax really is powerless. Stein was the power source and Jax the control element but still....