Honestly when it comes down to balancing ZF, I defer to the original plugin authors. They've been at it longer than I have.
Which comes to my next point: ZF is inherently balanced poorly. ZF has far too many variables in play to be balanced by the current mediocre plugin authors. Just check the
ZF forums. Countless people complain about balancing issues all the time. This doesn't even take into account the
complaints about perks.
I'm hesitant to change anything in ZF because it's pretty much an established game, but if there's enough players that want something changed, I'll see what I can do.