I personally think that (NETWIDE queries should be honored if from a
Listserv Postmaster or a NAD.  Even though I didn't say so earlier, that
was my original feeling when I asked about them.
The whole question was really of implementing it at all. period.
However, I thought that others would want general user abilities instead;
so I asked about that scope.
 
Now, it appears that I may have opened a can of worms!  ;-)
If global signoffs are so expensive, speed improvements seems the next
step.  Xedit restrictions may just be worth it.  Do you mean a list
would not be editable?  No Xedit or it would be like editing a TEXT file?
What about a special XL command for Xedit-List which would expand the list
to human-usable form and SAVE/FILE would "re-compile" it to "run" form?
GET/PUT of a list would essentially need to do this anyway.