You are welcome to try to install the 30 day free trial copy on each computer and see for yourself. I know that in Windows systems, the installer won't even allow an install into older versions of the OS, but don't know what you'll find with Mac systems.
Thank you for the response.
But I was hoping to get an response from someone who knew the answer. Something more than "try it and see what happens."
Question: Does FMP 13 work on Mac OS 10.6?
Not sure if this helps, on the windows side FMP 13 WILL NOT allow you to install on a box that does not have 7 or 8.
It would be a fairly simple "smoke test" to download the 30 day trial to one of the older macs and try running the installer. If it refuses to install as we find on the windows side, you have your answer. If it installs, then you'll need to research this further.