Excellent points! You're quite right that there are a lot more things we could do to improve the high availability in the Stack Exchange environment. Unfortunately, I was hired well after the environment was designed so any suggested changes would need to not only pass the rigors of review by the team but also be able to handle the load that stackoverflow.com generates. Changing pieces at this point would be nontrivial and difficult to get approval on if it meant that we'd affect performance of our main property.
That being said, I'm 100% in agreement with you that the two options you supplied would be wonderful additions to our environment.
That being said, I'm 100% in agreement with you that the two options you supplied would be wonderful additions to our environment.