I have a theory that since Revan was wearing his robes before he ever found the Star Map on Dantooine, he was Darkside then. His robes did not change to "Darkside only" with him, did they? Revan also wore his "Darkside only" mask there! It is my belief that Revan never "fell" to the Darkside, but was a Darksider all along. I doubt the Star Forge corrupted this "greatest of Jedi's". How easy was it for Darkside Players to "fool" the Jedi council?
Revan fell studying ancient Sith magics...Revan didn't study at Dantooine, he studied at Coruscant, so that means he was good at the academy until he started learning sith magics...as for the robes, he could've been dark by the time he found the first star map at Dantooine ( who even said inferred that was the first?), but you have to remember that Bioware needed to cloak him at all times, because they didn't want you to find out the twist...which wouldn't have been a twist...