[nkurz]

I'm still surprised at the level of efficiency, but glad to hear that you can back it up. I wasn't doubting that an underdriven LED would last that long, rather I was surprised that the remote phosphors would last that long without decrease in output. But reading more elsewhere, I now see that the lifespan of the remote phosphors can be excellent: http://www.digikey.com/en/articles/techzone/2014/apr/develop...

For others who are interested, here's another interesting link on the remote phosphor approach:

http://www.ledsmagazine.com/articles/print/volume-9/issue-7/...

And a nice overview of the efficiencies of white LED's, and where the losses usually are: http://www.sandia.gov/~jytsao/SSL_Trajectories_Proc_IEEE.pdf

The exact figure in the last are already somewhat out of date, but if you plug in the specs for the newer LED's, presumably the underlying physics hasn't changed.