Looks like a well made system and I'm sure you'll be happy with it. One thing about anything Jamie builds, there is a lot of thought process put into it as he is one of the smartest guys I've ever met in the industry, always thinking of how things could work better, be more reliable, etc. Good choice as far as a manual panel imo. Are you buying new or used?
That being said, I'm curious when you say "backup" what is the actual purpose? Are you looking for something to use in case your Starfire panel doesn't work and you can swap out quickly and still get the show fired? Or in case you find out something is wrong with your panel and there isn't enough time to get it fixed before the show date?