I run 8.5.3 on my laptop...that runs OS 10.9.5. Solidly. And then I share this license with my MacPro, running 10.10.5 and have no issues. We are running 10.10.5 at work, and MC 8.6.0, and no issues. But 10.9.5 is pretty good for me, The tower is on 10.10.5 for some software compatibility, and my laptop held back to 10.9.5 for the same reason, older software to function.