I’m a beta tester for Apple. I’m part of the “official” beta testing program called Appleseed. I am not an Apple employee. This is not the public beta or the developer beta. I’m running the second beta release, 11.0 Beta (20A4300b) and my 5D3 will not mount over Thunderbolt 3. It will mount over USB-3, but it is very slow. If your files on your Drobo are mission critical, I do not personally recommend going to Big Sur. This is not Apple’s opinion or Drobo’s opinion, just a user that has official access to the Big Sur beta releases. I hope this helps.