sheesh. It's better, faster, supports all the latest web standards. Just do it, you won't regret it. FF10 is the new LTS option, so it will be the most stable option going forward, but personally I always have to be on the bleeding edge and am on nightly-ux FF13.
Why did they use this measure? With Mars being so much smaller, of course a higher percentage of the volume would be hospitable. Mars has 15% of the volume of Earth but 28% of the surface area. Just seems like bad comparison.