Thought about it, for different reason though and decided it is not worth the hassle.
Everyone has different tastes, so you would end doing the fork for small amount of people anyway and some of the stuff you mention is doable by mods. While main fork is in active development and maintained relatively well, that is.
Balancing would be likely welcomed in mainline too… though there might be different opinions of what is balanced and what is not and final decision would not be up to you, which can be an issue.
I don’t know… how Reaper’s fork is doing?