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You do. Make a bootable USB installer of HS using Boot Buddy or Install Disk Creator, then boot from that to install just the OS. I would advise first cloning your main drive with SuperDuper or Carbon Copy Cloner, rather than migrating everything from TM. Re-download any Mac apps from the App store and non-Mac apps from their sources or the clone. Migrate the files you want from the clone. You can be selective, or do it en masse if you don't want to use this opportunity to clean out unused/unwanted files. If you find any problems with HS, you still have the clone of your previous system to quickly get you back up and running (faster than TM).
 
You do. Make a bootable USB installer of HS using Boot Buddy or Install Disk Creator, then boot from that to install just the OS. I would advise first cloning your main drive with SuperDuper or Carbon Copy Cloner, rather than migrating everything from TM. Re-download any Mac apps from the App store and non-Mac apps from their sources or the clone. Migrate the files you want from the clone. You can be selective, or do it en masse if you don't want to use this opportunity to clean out unused/unwanted files. If you find any problems with HS, you still have the clone of your previous system to quickly get you back up and running (faster than TM).

Thanks! If I want to get back to Sierra, do I need to reconfigure the drive from APFS?
 
Maybe not essential, but advised. Many people in the FCP X community had problems with HS at first, except the ones who waited a version or two and did clean installs. I waited until 10.13.3, did a clean install on a new SSD and tested until I was satisfied that everything worked, then cloned that over to the drive on my late 2013 rMBP.

i run FCPX (and keep it up to date), and all is well (or well enough). not convinced that a clean install is necessary (unless, of course, it is for a specific reason).
 
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