Personally I refuse to see the pathetic character in the s**t episode in season 6 as Kes.To me the most important difference is that in Warlord it isn't really Kes that goes evil, but 'just' an alien posessing her body and suppressing the 'real' Kes, whereas in Fury it is Kes herself that goes down a malevolent path. Even if in Warlord the damage would have been irreversible, and they would have had to kill Kes to get rid of Tieran, it wouldn't have stained the Kes memory for me. (Though in that situation I'd probably complain that it was an extremely lousy way to write someone out of the series.)
Despite a slight resemblance in looks, I see nothing else which proves that this was Kes.
The real Kes would never harm her friends on Voyager, she would rather sacrifice her own life.
Not to mention that the story itself is so full of holes and contradictions that anyone could wonder what moron it was who wrote the story and why that person was hired in the first place.
It was all about destruction of a character and to insult the fans of that character.