I'm sure you two know the details, but for anyone else reading this it might be good to expand on the "that can't have IP phone licenses". I'm not an expert on licenses, but I would have thought that you'd still need the licenses even if it's a secondary controller?
When I first read this, I thought it said "that can't have IP phones", which caught me as odd. Since you can, it just depends on what you are protecting against.
From what Lou describes (having IP phones), that is a setup to survive a WAN or primary controller issue. To be a true 'analog branch office' you would use ONS sets (maybe not exclusively, but at least some) to provide survivability in a LAN outage. Maybe splitting hairs, but a distinction that some may not pick up on.