I have an early 2009 Mac Pro running Yosemite 10.10.5. I use it mostly for Premiere and After Effects CC 2017. I was using FxFactory's free transitions for Premiere (especially Andy's swish pan and dissolve) but now they don't work with CC 2017. There is an upgrade for FxFactory but they won't work with Yosemite. I need to upgrade to El Capitan or Sierra. But the Apple website says those OSes are only for Mac Pros 2010 or later. Has anyone upgraded to either of these systems with a 2009 Mac Pro? If I try using El Capitan on my machine will it screw it up? Thoughts?