I'm on the inverted position side. I use all the hand positions mentioned but the one that I find most advantageous is around the front of the bars. Here on the east coast it seems the wind is always blowing a gale so I spend a lot of riding time in an aero tuck, elbows in, holding as far forward and close together as possible.
I've had the trekking bars on my hybrid road bike for more than three years and just bought a new Trek Verve, (hybrid trail bike?) and the first mods were a new seat and Trekking bars.
Just in time cause the wind "she's still a blowin'!".

I have my mirror on the forward curve as for some reason I never put my hands there but on very long rides I do occasionally use the rear curve, as a last resort.