>"I don't know that you can talk about 'trail shoes' and 'trail runners' generically."
Good point. I (mostly) quit wearing boots about two years ago--since then, I've worn out two pairs of Keen Ridgelines (light-ish, but fairly padded and have a shank-like stiffener in the sole) and have just about worn out my first pair of Inov8 Roclite 295s. The Inov8 are as minimal as I've worn, and I'll probably get another pair then maybe go lighter still.
I love the 295s--in the past four trips, I've had them in every condition I'm likely to hike in: doing high daily miles (for me), crossing several miles of snow, uphill and down, on muddy trails, very rocky trails and off-trail talus, scree and gravel, stream crossings, cheatgrass, and pavement and sidewalks around town. I've noticed that my gait has shifted more to the balls of my feet (have experienced some bruising to my arches if I don't, esp. on rocky trails). Great traction, wet or dry, due to lug soles and "sticky" rubber. Some soreness in the tendon running from big toes across top of foot, if I'm hiking 15 miles or more with significant elevation change, but nothing debilitating. I suspect this is a foot strength issue, as it started in the dominant foot, disappeared, then started in the other foot.
Weight carried as stated above: sometimes below 15#, and as much as 25#.