I don't see why we shouldn't take his identity at face value (hehe accidental puns), at least until proven otherwise. I don't think Vendetta Chris looks like the Chris from 5 and 6, but I'm not about to question his identity because of it. I mean, would people be having this debate if the guy at the end of the game said "I'm Chris Redfield", wore BSAA attire, and flew away in a BSAA/unmarked helicopter? I think it's possible that we could be asking the wrong questions here. Let's assume, just for a moment, that it is in fact Chris Redfield. The discussion of his physical appearance becomes arbitrary, so let's put that aside. He introduces himself as Redfield. Perhaps its not his MO, but people are not defined by the form of their introductions. That's not to say that people's mannerisms are not defining characteristics, because they are, but I can guarantee that I've not introduced myself the same way to everyone I've met. Not only that, but just the words themselves seemed uncharacteristic. His tone seemed perfectly normal for the Chris we know: somewhat gruff and perhaps curt, but not unkind. Then we have his attire. His getup is most likely a product of the organization with which he is associated. He wore STARS clothing in 1 and BSAA clothing in 5 and 6. Essentially this means that if we take the shift in organization for which he works at face value, the clothing he is wearing is not in itself unusual. Which brings me to my final point. This guy is linked to umbrella. The Chris we know would never work for, or even associate himself with, the umbrella we know in any way. No matter what. This means, that should Chris Redfield indeed work for umbrella, either Chris changed, or umbrella did. So the question then becomes, what happened? What changed? Why is Chris working for umbrella? How does umbrella even exist? What does umbrella now do? Did Chris become a bad guy? If so, what caused it? I don't mean to suggest that it's impossible for this guy to be someone other than Chris Redfield, but there's more to consider than just that he might be an imposter.