At this point, that looks like everybody except Pender agreeing to go (with Siobhan abstaining)- given that horses probably won't help much in the swamp, we ought to go owl-riding, I guess. We ought to be able to acquire more horses later, somehow, and I really think we should take any chances to move quickly- who knows what the horde is up to while we're slogging through the mud.
On a semi-related note, did we get any XP for that fight? Some of us are close to leveling, and a restful night in an elven village might be a good idea there.