I never more than played around with high power LEDs long enough to not care for the efficiency.
The failure rate I was considering is in commercially produced devices. Maybe nobody is doing it right. I didn't design any of those.
The 100,000 hour rating is good for colored, standard type, LEDs. Not white LEDs. The phosphor in white LEDs degrades the life to more like 20,000 to 35,000 hours at best. Some manufactures have revised the life expectancy of white LEDs to 5,000 to 10,000 hours. I saw one manufacturer list 2500 hours. I expect the high power LEDs, even the little spyder LEDs to be even less. Heat decreases the life of all LEDs, and high power LEDs are hot.
I didn't mean a single 5mm LED is brighter than a 3W. I meant an array of 50 or 100 5mm, using the same total power as the 3W, would be brighter.
The high power LEDs have reverted to old, less efficient, technology, to help get the heat out of them. That's pretty much how they can take so much power.
As far as efficiency.
A regular old bulb makes 12~15 lumens/W.
The best sorted and ranked LEDs, commercially available, are about 30 to 35 l/W. Nichia has one ready to come out at 37.5 l/W.
The stuff from the 'surplus' catalogs is not going to be anywhere near 30 l/W, maybe more like 3 to 10 l/W.
CFLs make at least 50 l/W, usually considerably more.
The cream of the crop, sorted, high power LEDs make about 25 l/W. Less than half a standard CFL.
I expect the standard type supplied to a hobbiest to be maybe 18 or 20 l/W. An increase of 50% and it will catch up with LEDs I can get right now.
For a lot of efficient light, CFLs win hands down. And they are cheap too.
The only high power LEDs I burned out was done on purpose. I need to know what they can, and what they can't take.
So no, I won't buy into the hype quite yet. This American will leave those in the bag for a couple more years.