Either boot should work but the Spantik is warmer. If you're only going to bring one boot I'd probably lean towards the Spantik in case it gets super cold up high. You could probably make either one of those boots work though. It makes it a little easier to start with warm boots since you are starting from huts on those peaks. If you start with warm boots you're more likely to keep your feet warmer for longer than if you are putting your feet into an ice block at the start of your climb.

Apologies totally off topic.... but Kurt I read your 2008 Everest trip report yesterday. Great read. Thanks for sharing.

I have a similar question, as I have the Spantik and Trango Extreme Evo Light GTX. I was leaning towards the Trangos as the Spantiks seem like overkill on these mountains. I don't want my feet sweating off. What kind of temps can we expect?

I just looked at some old pictures, I wore my Mad Rock Mountains to about 18,500 feet on Cotopaxi. Didn't summit, but not due to cold feet.
Edit: Though for Chimbo, I'd probably go with the Spantiks...