This seems to be the only issue that I have found with my specific system and unfortunately it's a big one! I use UAD powered plugins on all of my mixes because frankly they sound incredible. I know that UAD have been reporting this bug with Sierra since the beta was released but I was kinda hoping that the Final Release would magically fix the issue, because that always happens, right?
Mac OS Sierra isn't officially released for a few more weeks so hopefully that will give UAD enough time to fix the issue and everyone can enjoy Pro Tools without the laggy graphics!
List of Plugins that I have briefly tested and seem to be working OK (I haven't tested advanced items like automation)
Antares Auto-Tune LIVE
Eiosis De-Esser
Brainworx BX Meter
Lexicon LXP Reverbs
Massey DRT
Native Instruments Absynth
Native Instruments Battery
Native Instruments FM8
Native Instruments Kontakt 5
Native Instruments Massive
Native Instruments Reaktor 5
Relab LX480
SSL Duende Native Channel Strip
SSL Duende Native Bus Compressor
Slate Digital Everything Bundle
Slate Trigger 2
SoundToys 5 Complete
Waves (Various Plugins)
VocAlign Project
CONCLUSION
Early signs suggest that this might be the rock solid operating system that we have all been waiting for since OSX Mountain Lion was dropped from software developers supported operating systems. Obviously that could all change in the blink of an eye and it also depends on how long it will take Universal Audio to fix the issue with their UAD cards!
So, if you don't have any UAD hardware, it looks pretty promising! I'm not saying you should upgrade as soon as it comes out but hopefully this will give you a small insight into how Sierra might affect your pro tools system.
As always with these things make sure you create a backup if you decide to upgrade!
10/09/2016 UPDATE:
There have been a few people that have managed to disable the System Integrity Protection (SIP) in order to enable the drivers for their UAD gear. This isn't true in my case. I managed to to disable SIP but it only caused the OS to hang and crash when loading the drivers for the UAD-Quad. It looks like the people that have managed to get this working successfully are using external devices such as the Firewire or Thunderbolt Apollo and UAD Satellite, whereas I am using the PCIe UAD-Quad. If anyone has managed to get their PCIe device working I would love to know!