As an extension of the READ_ONLY feature it would be useful to configure that is_superuser can still read and write. Possibly a flag like READ_ONLY_UNLESS_SUPERUSER.
Thanks! Applied here: https://hg.code.netlandish.com/~petersanchez/django-impersonate/rev/a70be42b2e05d6a6a67cc93eae3f3b1b812122ff