I've used mine for an estimated 5 hours of intermittant use.
It was at maybe 50% brightness compared to new batts. Still eminently useable.
That is why I prefer UNregulated lights. They don't suddenly die on you.
The 3AA has become my work light of choice, because of it's good run time, and grip-a-bility. Getting a bit beat up from being under tractors, car hoods, and the like.
I would not be surprised if it out outshined an Infinity Ultra at 28 hours.