Madara didn't have both hand seals.
They certainly add on significant additional powers, including one to make a moon sized CT.
I believe that if alive Hagaromo didn't have those seals, he would only be about as strong as Madara.
True S06P Power= Juubi Jin+Double Rinnegan+Ying/Yang Seals.
Madara was missing 1/3 of the complete puzzle.