So, I cant read 1000 posts on this so I'll just chip in with my opinion.
Janeway was right.
Tuvix is a freak accident. No history, no family. Is it unfortunate, even tragic? Yes.
But what would have been more tragic is abandoning two men with lives, with careers and [in Tuvok's case] with families to die. Janeway could not afford to let sentiment get in the way of restoring two real crewmen who were forced together to create a hybrid.
Sure its uncomfortable. Its meant to be. However, in my opinion, Janeway made the only real choice there was: fix the mistake and save two lives.