Just a random thought here, but I was wondering about Genre specific groups, rather than simply dividing discussions between "Authors", readers and "Editors". Say creating a "Sci-Fi", "Mystery" or "Erotica" group. That way readers, authors and editors of specific genres could congregate to discuss common themes, rather than each feeling relegated to specific areas (not that the current listings seem to restrict anyone anyway).
Initially, I'd suggest picking the largest genres on SOL, say "Sci-Fi" and "Erotica", and if those catch on, then we could subdivide them into more precise groups like "Do-Overs", "Time Travel" or "Incest". If they don't catch on, then introduce them as a "Beta test", so when they flop you can simply delete them and return to the current setup.