I love bare feet too but can't really get it to work on the mtb I ride -1991 shogun TI - I find havaianas work well though as a compromise and I ride in these year round (Sydney Aus)nearly all the time unless it's a bush track
The havaianas upper sole pattern is about the least slippery you can get also they are very light
I have a pair one size down so they stay on my foot when I pull out of the pedal cage
So, today, though i happenned to be in a bike shop saw these BBB MTB nylon pedals. $19.99. i thought id give these a try they are nice and light, have a good edge round the front to curl your toes around and out of the box are good for maybe 5 miles. I rode 20 in them (30 km) which exposed a few flaws, notably the sharp edge round the front and the protruding bumps are a bit high for shoeless comfort. 5 minutes with the grinder, i took the edges off and these are so comfy! Even so, 30 km absolutely shoeless- i have never felt so good after a ride.
Ill post some photos of my mod if anyone wants.