I'm not saying that would be given immediately the degree and the confidence that they had earned Tuvok or Neelix. He would have had to earn. Once this is done, yes, for me it would have been made in command. Take Seven of Nine: At the beginning she was discriminated against by all, more than half the crew was against her. Then by the time she has earned the trust of everyone.
The point however is not that. It was a living being, it was alive, was sentient. For me it would haven't to die.
However, given the situation, given all the pros and cons I would have done what Janeway did. I also would have done back Tuvok and Neelix, I just say that it is still murder. Although Tuvix includes two people is a sentient being and deserve to live.