Specifically, I've got a 2009 Mac Pro (5,1) that can run Mojave, but my 2010 MacBook can only run up to High Sierra. Wondering if two of my Macs on different generations of macOS would cause problems (e.g. '09 Mac Pro is on Mojave and the MacBook on Sierra)? Both Macs still on Sierra because of the problems I read about High Sierra. And haven't bought a new MacBook because of the butterfly keyboard issue.