It’s interesting that the ending was changed so much, that it went from a foregone acceptance of his plight by Tuvix to a moral standoff. I do think it’s remembered due to that change but I can’t help but think, character-wise, it doesn’t strike me as very cohesive. I haven’t rewatched the episode in ages but isn’t it implied that Tuvix is a combination of Tuvok and Neelix in personality, strengths, knowledge etc as well as physicality? Tuvok who would stoically sacrifice himself for the good of the many and Neelix who would do anything for his friends and somehow, combined, they approached their separation not with resigned acceptance but panicked protestation.