Ooh damn. Lol you're braver than I. I've traversed the abyss more than a handful of times but seem to be the most successful with my Hunter. Another thing most people don't pay attention to in that part of the raid is how insanely useful the Icebreaker is. In dealing with a whole mess of Thralls, Firefly pretty much kills off an entire swarm with just one bullet. You should give that sniper rifle a try the next time you find yourself in the raid. :)