Some good observations. I am a big fan and critic of XC racing flats for hiking. Biggest con is they do not last very long, so that is not good. Also they do poorly in cactus infested environs, but I can live with that. Lastly, most provide really poor traction.
As far as sore feet, that is going to vary by individual, amount of hiking done on a regular basis, hiker's physical condition, weight of gear, etc., etc.
I can hike a lot of long days without sore feet, but I suspect I am going to be a minority here.
For the past several months I have been hiking in a pair of Mizuno Wave Universe 4 XC flats. I don't think a lighter shoe is made by anyone. I got these fairly large so my feet could spread out. And even though they are really longer and wider than what I normally wear, they have worked well. The ankle/lace area can be snugged and I never feel they are too loose in the back of the shoe. Total drop is around 4mm. It looks like the midsole is starting to crack just in front of the ball of my foot. The insoles are glued in so I am not going to take them apart. I am getting longish bumps across this area that can be felt. Doesn't hurt, but I know it is there. The mesh has really held up well, which surprised me. Also the mesh is very fine so my feet don't get a dirty from dust as all my other shoes. They are so light, they feel like hospital slippers.
I have used several different brands of the lightest XC flats over the past several years, but the biggest negative is the lack of a rock plate. I guess I am going to try the MT110's when they come out. I haven't used any of the MT series in the past. But I am a big advocate of the lightest shoe possible.