I was thinking after re-reading the last ten chapters: Why does Madara wants The Sage Mode from Hashirama besides the fact that it is the only weakness of the Jubi Jin????
The answer:I think we don't know all the abilities of the Sage Mode, something that only Madara knows..Maybe Sage Mode + Rinnegan = A new Ocular power, greater than the Rinnegan...Who knows..?
What are your thoughts about that???