Well, after a successful update of two Mac clients to the new OS and after updating their ancillary software, I started the Symantec upgrade.
First, uninstalling the old Symantec Endpoint client. Support had provided two articles to accomplish that (mentioned previously). Only one proved useful. The first referred to finding something in the SEP_MAC folder; I am assuming this was from a full SEP/SEPM environment, because the cloud version doesn't have that folder. The second referred to downloading a zipped file and running the expanded dlg file. Unfortunately, the OS intervened with that with the following notice:
What was strange was that I was logged on as the administrator with a non-blank ID. Support eventually sent instructions for how to handle this situation, but that came in later in the day. In the meanwhile I followed the second set of instructions and used the Terminal to remove the program. Reboot followed.
After that came the new installation. It was standard and uneventful. Open the PMC, select the client to manage and open their Hosted Endpoint page. Click the Comuters tab and select the new Apple logo'd "Unmanaged Computers" link. Enter the name of the computer and download the installer. Click the installer to run and a few minutes later you've got Norton (ahem) installed. On one machine, I could not get Safari to open the Hosted Endpoint page from the PMC, so I used the send email options. Screen shot from a Windows machine shown below:
After making sure that Live Update completed, I ran a Quick scan. Neither Mac had any issues, and for that I was grateful.
Regrettably - and because this is still a beta program - those two machines still do not appear on the PMC. And there is only the barest evidence of them on the Hosted Endpoint page.
So I have no idea as to their status. No different than before, but irksome nonetheless in 2016.