Vale is a strong and well defined female character. I'd sooner see any canon regular male character killed rather than Vale. Vale is in many ways the spiritual successor to Tasha. Also, Vale is played by Katee Sackhoff in my mind brain.
If they were gonna get rid of anyone, I'd suggest Chakotay, Harry Kim, Will Riker, Wesley Crusher, JLP, Jarem Kaz, or Vaughn. I'd pull names out of SCE except the last one I read was Wildfire and I can't remember who is still alive. :/ David Mack. Oh! That's one more thing I forgot to mention. Next major character death, please give it to someone other than Mack. The man is a dangerous psycho leaving a trail of death and destruction throughout the entire trek lit universe.
Granting, for the moment, that she is a strong and well-defined character, that doesn't mean that I have to like her, nor does it mean that she should be immune from the universe. Spoiler: The Persistance of Memory Hell, Jasminder Choudhury was also a strong and well-defined female character, moreso I think than Vale, and look what happened to her. As I said in the Fallen Gods review thread, I find Vale immature and unprofessional these days. I don't have the book with me right now, but I recall her acting ridiculously gung-ho throughout. None of the moderation I would expect from a freaking XO. And I disagree about her being the spiritual successor to Tasha. Tasha was rarely so hot-headed, and was always a consumate professional. In some ways, I would say that Šmrhová is more Tasha's successor than is Vale, although she's very different in other ways.