I upgraded to Sierra and I am glad that I did. The OS feels much faster and lighter than El Capitan and the new optimized storage features are certainly a welcome addition. Logic Pro X appears to be working much better than it was on El Capitan and best of all, I am no longer having audio drop outs / distortion when using applications such as iTunes.
After copying over all my useful content (such as music, photos, videos etc.) from a backup, my first step after installing a new OS was to create a backup. For this, I used Time Machine. The backup when through just fine with the exception of “iCloud Drive” which took a while to download content during the backup process. Once all iCloud content was downloaded, the backup process was complete.
I opened up Logic Pro X and tested it without any 3rd party plugins installed. The DAW was as fast as its ever been since the OS X Mountain Lion; certainly a plus in my book. The next step was to install 3rd party plugins. Many companies in this area have warned users not upgrade to Sierra yet. Of course that did not stop me as I tend to keep 3rd party plugins at minimum. I opened up Waves Central and installed a local backup of my plugins after which I authorized. At first it did not authorize but this may have been due to the unstable internet connection at the time. After trying again it worked.
I opened up Logic Pro and my Waves plugins were fully operational. Recorded, mixed and mastered a song. Performance wise the improvements are certainly visible.
Plugins from Plugin Alliance do not work officially yet as told by the manufacturer however, I found a temporary solution that will work until the problem has been officially fixed. See below:
First copy the auvaltool file from the /usr/bin folder from your El Capitan install on to a USB Stick.
Restart your Sierra install and hold down Command + R until you see the Apple logo and loading bar.
Once in recovery mode, Open Terminal from the Utilities menu and type csrutil disable
This will disable System Integrity Protection, which will enable you to replace the auvaltool on Sierra with the one you copied from El Capitan. Be sure to keep System Integrity Protection disabled while you use the previous auvaltool otherwise the it will not work anymore.
Once a fix is officially released, simply replace the auvaltool you copied from El Capitan with the one installed by Sierra.
Reboot your Mac and hold down Command + R until you see the Apple logo and loading bar.
Once in recovery mode, Open Terminal from the Utilities menu and type csrutil enable in order to re-enable System Integrity Protection.
After following steps 1-4 you may need to configure file permissions. Do the following:
sudo chown 0:0 auvaltool
sudo xattr -c auvaltool
sudo chmod 755 auvaltool
Disclaimer: Please note that this temporary fix is not endorsed by Plugin Alliance and you must use at your own risk. Plugin Alliance say that they are working on an official fix. SIP must be disabled in order for this workaround to work and should be re-enabled as soon as an official fix is released by Plugin Alliance. Disabling SIP (System Integrity Protection) poses a security risk and should only be disabled when it is absolutely necessary.
Once again than you all for the support.
Download: auvaltool from El Capitan