Thank you for your support and the feedback, we are glad to hear it is helpful!
RE: filter by elevation, this is a great suggestion and is possible. But probably not easily available because there's no easy way for us to hijack Redfin's home rendering process. We can definitely look into this later but our guess is the best we could get is probably some sort of polygon based on the elevation of your choice.
That being said, we probably won't be able to get to it till next year because we will be focusing on the rewrite of our extension and website for the rest of this year.
But we also don't want you to be disappointed 😀 We've already submitted a new version that enables the additional terrain map type, which should be available in the next day or two once approved by Google. While you won't be able to filter by elevation, but you can at least see it on the terrain map.
Hope this helps to reduce some immediate challenges that you are having.