Personally, I would vote no. I like to post about pinball here, but to get help I prefer the pin section at KLOV. Why? Because there are several experts that help out there. D_Zoot drops in here from time to time, but the others don't.
If there became a sub forum for pins, it would become yet another section I don't visit. And don't even consider a daughter board, everyone forgets they exist as soon as they are made.
Stick with arcade misc - that way the action in there stays pretty regular.