Bringing Janeway back just to have her die again would be stupid. And would be playing with the minds of the fans that do enjoy her time on Voyager. If the end result in bringing her back is to die again then I say just leave her dead. Janeway was the only female Star Trek captain to lead a series. Out of all 5 of the captains Janeway is the only one to have been mishandled and what others says is true. Like Nick Meyer said, of course you can kill Spock as long as you do it well. Janeway's death was not handled well.
I have to say I've read both Full Circle and Unworthy but haven't read Children Of The Storm. I've been reading Trek novels for more than 20 years and I have to say that this era of novels has produced two of my favorites, DTI: Watching The Clock and Full Circle. I've read them over and over and never get bored in reading them. I'm hoping that Eternal Tide will be just as good and have faith it will.