I just went to edit the information on one of my super users (through the backend -> Users -> Manage), which I haven't done in quite some time, and was surprised to find that I was able to edit and save the info even though I have "Disable editing backend users' properties" set to "yes." Usually I have to change it to "no" in order to edit my super users info, at least I had to in the past. But I had forgotten to change the setting first, and then was surprised when I was able to save the changes anyway.
I have no idea what I might have changed except for the myriad of Joomla! and extension updates over the past several months.
Thanks!