Hello Slinger,
Welcome to CPF.
The PowerFlare is a great product. I have a bunch of them.
My wife used the ones in her car about a month ago. Someone had slipped into the ditch across the road and their car was still sticking out on the road, but they had turned out all their lights, or their lights stopped working. She loaned them some PowerFlares to keep traffic away until the tow truck could show up.
Real flares would have also worked in this case, but I don't trust my wife with real flares...
I have used mine a lot, but not in emergency situations. Food delivery, "Look for the flashing beacon in the window." Marking the beginning of a contest, "Line up on a line between the two flashing beacons." I took a pair with me while kayaking and used them to mark the best landing zone on a rocky beach. My son fastened one to the back of his bicycle and went for a ride. The local police pulled him over asking for information on the PowerFlare. They were impressed with the side, as well as back, visibility. I had a nice chat with them.
I have both amber and red LED units. After an afternoon and evening of testing, a group of people finally settled on the fact that red seems to be more visible in daylight conditions, however at night both amber and red seem similar in brightness.
Our vote for the most "noticeable" pattern was rotating for both red and amber. Second best was quad flash.
No one was impressed with the flashlight mode. They all figured that constant on high or low would do just as well.
The younger generation thought the strobe mode was "really kewl..." but even they agreed that the rotating mode was more noticeable at greater distances in the daylight.
At 1000 feet in bright sunlight, you first notice the color of the unit, then you can see a flickering light. While not optimal in bright sunlight, I think it does get the point across that there is danger ahead.
I haven't tried putting a cone over one of them. That should be interesting.
I ran some R-CR123 cells and they did fine. However, the battery holder had to be slightly modified to handle the extra length of the R-CR123 cells, and when the protection circuit cut off, the PowerFlare shut off. With a CR123 battery, as the battery dies everything just dims down and slows down. If you are running them every day for short periods of time, the R-CR123 option would be worthwhile, but for occasional use stored in a car, I would stick with the primary cell.
They are a little expensive, but I am impressed with them.
Tom