These are helpful ideas… thanks. I think I am looking at a few aspects here and it’s worth looking at them in turn.
The Admin vs Moderator vs leader topic is helpful in elucidating the difference between TL4 and moderator and admin. In short, TL4s can moderate in topics, but moderators can also manage users. I did a quickish test just now and can see that moderators are able to access some admin functions on users, including silencing them. They also have access to some potentially confusing admin dashboard stuff including plugins and logs.
So… while in most cases there is no harm in giving forum moderators access to full moderator privs, it may confuse them and involves me telling them to stick to what they understand and need to moderate discussions and me trusting them to do that. This is not an entirely bad way to operate but comes with a bit of risk. Some of the concerns raised in that topic have been fixed - e.g. moderators do not necessarily have access to email addresses (admin settable) and they cannot download user list or user data of others.
My preference still would be to have a separate group for forum moderators and display members of that group on the about page, and to give forum moderators TL4 by default and upgrade them to moderators as they grow into the role.
I think this has come up elsewhere on meta - we don’t need to talk about hardening security of admin access here.