In /usr/share/emacs/21.3/lisp/mail/supercite.el in function sc-header-verbose
I prefer the result of “(sc-mail-field "subject")” to get quoted itself.
That's easily achieved there.
I actually created /usr/share/emacs/21.3-johayek/lisp/mail/RCS/ to maintain such changes.
Obviously .../21.3-johayek/... from a configuration management point is not a name, I really like for maintaining these changes long-term, but ...
I left the standard setting of gnus-summary-line-format
(which is "%U%R%z%I%(%[%4L: %-23,23f%]%) %s\n"),
and changed it to be "%U%R%z %o %I%(%[%4L: %-23,23f%]%) %s\n".
I did that, because I think, displaying the sending date ("%o") of a message is rather convenient.
I love the threaded tree display of messages in the summary buffer.
You can fine-tune your own threading style using gnus-summary-make-false-root.
I use gnus-summary-make-false-root=nil,
so that loose threads do not get gathered.
Loose threads are also created by frequent message subjects such as:
“Hello”, “News”, etc.
And I don't consider it reasonable gathering them in any way at all.