That's not really my concern, and I don't mean to accuse you or imply you will do anything of the sort, but the idea of a player who actively participates in WoE being in charge of class balance is iffy to me.
I'm the type that will class-hop to what I perceive to be a stronger class, and with 15x rates and a 175 cap, making a ton of characters does not sound fun at all. So to me the safest course of action is to follow your class.
Do you see what I'm saying?
That's my main point against custom balancing classes and skills. Unless the person in charge of all the balancing isn't actually playing, in which case not only does the person have no perspective as they're not active in WoE, but they have little to no incentive, as I imagine your pursuit of a good renewal server is to be able to play in it and have fun.