I too completed Pinnacle Gully in the dark (we had had to wait for a party above to clear the climb) and solo (my second had backed off after the first pitch). I had never been down the Escape Hatch, so I headed directly for Lions Head. My only problem was postholing through a snow slab on the descent and being left hanging upside down (on the surface) with my foot stuck under the slab. (Had to smash the slab with the my ice axe shaft to escape.)
Fortunately, not as humbling an experience as yours. (The night was clear and the view from the Alpine Garden was very nice...)
Doug