First off I think full kyuubi could take on Pain and win. Jiraiya nearly got taken out from a fraction of an already 1/2 powered kyuubi and he's fighting with pain evenly(so far anyway).
But my primary reason for replying is about the Pain being stronger than Tobi(Madara) post. I don't believe this is true, just my opinion. When Tobi says Pain is the leader he also say "We won't tolerate failure from the leader", which implies he(Madara) and others are still above Pain, just not in the Akatsuki organization. He also seems to be giving Pain orders. Pain doesn't seem like the type to take orders from someone lower than him(since he believes himself to be a GOD). Just my opinions, replies welcome.