Here is my Shadow VG-10 in action in a pitch black mine:
We spent about 3-4 hours down there and I use it at max for about an hour I'd say maybe a bit longer then the rest of the time on medium. After an hour or so on max it begins to blink on and off, I guess to indicate that the battery is not juiced enough so drop it into medium and it will soldier on normally. The blinking is not described anywhere in the item description though so was a bit confused at first.
We need more real world in use shots in this here thread!
Edit*
One of the explorers with us that day had a tri-XM-L Sky Ray type torch but it was WAY longer and bigger, it was +2000 lumens and she said she could get over an hour on max brightness out of it. It was so big she had a shoulder strap for it...I was impressed!