i'm primarily a trail runner and use hyperspeeds (v2) for road and track workouts and races, and don't think they'd do well on trails, largely because stuff would get caught in the cutouts in the sole, and also debris would easily find its way in during creek crossings and irritate the feet thereafter.
my everyday go-to trail shoes are the new balance 790s and, more recently, the NB 100s; i've raced a trail marathon in the 100s and everything up to 50 miles in the 790s. both drain well and certainly qualify as flats meant for "real" trails. i wouldn't, however, recommend them for desert-like terrain where every step brings you in contact with sharp rocks, because part of what makes them great shoes is the intimate relationship they offer with the stuff underfoot.
note that the 790s have been discontinued, but there are online outlets that still offer them in men's sizes at good prices; alas, it has become tougher to find the women's model.