We have 3 computer set-ups in the studio with various digital workstations for recording and editing. The only thing preventing us from using the Apollo 8 room is UAD. We want to use Sierra, because it's newer, better, faster and a more stable operating system than El Capitan on our computers here. I think it is very reasonable to expect software companies to keep up with the demands that confront them and be timely about driver releases. It's ridiculous to make excuses. I certainly don't get to make them with my clients and I would think a company that bases itself on professionalism would back up their word.
As to the comment about Sweetwater's list of compatible software, when has Sweetwater ever been the last word on anything musical? I ran my own tests in a real world setting and I can tell you, that aside from UAD's FAILURE for compliance, everything else is fine. We are looking into Apogee replacements for the Apollo 8 and will no longer purchase any UAD products.