Cichlid, I told you the job is at Duke University :P
Fiesta, the LEDs should have 70% intensity at 10 years. If you keep them cool and underdrive them they should last much longer than that. They pay for themselves just in bulb costs at year 5 (add an $800 fixture to that equation and you can see how the savings really pile up). If you factor in electricity savings (not really a concern for me...) it's probably 3 years compared to metal halide or 4 years compared to T5's.