I like the idea of new guild ranks because I've known Officers a long time ago who just went off the handle thinking that they can eject whoever they want even though I forbid Officers ejecting in PIC. With a Co Guildmaster rank, that would separate powers within a guild and also clarify the limits of one's power for the better instead of more less "make believe" guild positions in which people (not anyone in PIC) would take advantage of for not being an offical POTCO guild position.
Plus, I have some people in PIC who deserve more than just an Officer rank. Guildmasters being able to promote above the Officer position would be more than awesome for me.