Control/admin buttons are an unrealized stop gap for not choosing a sufficient frontend/emulator/encoder combo.
Ideally, you wouldn't want to have any extra buttons.
I'm redoing thing in my set up. Most often I play classics, I don't need a 7 button fighter. I'm switching to a 4/8 joy and a neo-geo layout. I have spinner and I might use it on the same panel, despite what I say about frankenpanels.
My key advise is to wire up a panel, paint it flat black, no artwork and test it out for a few months. You may decide to change it. You may beat all of the brawlers and not desire to play them again, etc.