Lance, From what I ciphered (before I went insane from reading light buld tech specs) is that led's give up 166% more lumens per watt at minimum. The biggie is that the lumenosity is focused and drills way deeper into the water.
That said, I could find nowhere where an outfit would say "just use led's on your tank". The best outfits say you should use them to compliment your other lighting for technical reasons as an advantage.
They just aren't ready for primetime yet, period.
If you're trying to use a watts per gallon comparison, led's require 14-28% of wattage for the same amount of useful light.
Here's an awesome writeup on all types of aquarium lighting. The reading is about as dry as a popcorn fart, but there's lots of great info if you can stand to read it. It's recent, and was just updated 4 days ago.
All that said, the two fixtures I picked should be a good direct replacement for my t5's. I'm not gonna chance it, though. I'll just get some new lamps and keep this fixture for another four years if it'll last that long. By then, price should come down and all the bugs should be worked out.
