The thing with Chess Xehanort's silver eyes is that Young Xehanort had yellow eyes before the time travel. And that stuff is supposedly before he left the Destiny Islands. At least in his render. Not sure if we see his eyes in-game.
As early as his appearance in Olympus I was expecting him to be someone from the Chi era. I was more leaning to him being the MoM from their shared manneirisms so I was still taken by surprise when he turned out to be Luxu.