Well, I discovered the secret to doubling the growth.. big fan over the screen. I put a 10" fan over it for the last week and I have had to clean the screen twice within a week, both times the screen was stuffed full, so full my emergency overflow was kicking in. I cleaned it last Sunday then put a fan over it to keep my tank cool due to warm weather, and by Wed the screen was full.. so I cleaned it Thur morning and had to clean another full screen Sunday.
So for right now I am going to say that LEDs work great on my ATS, although with all things LEDs, there is no "one answer fits all". Distance from the screen and choice of optics play a role in amount of LEDs. Right now I am not really saving any power with the setup I have. If I refined it a little more I could take out 4 LEDs and add 80 degree optics without sacrificing growth. Only benefit with going LEDs vs CFL or T5 is the lack of need to replace bulbs, but up front cost for LEDs is going to offset that for quite a while if you use 23/26w CFLs. Power wise you won't be saving much. So I have to agree with Santa Monica in saying that LEDs on an ATS are still "experimental" because while yes, they do work, they are certainly not for everyone and a CFL setup will do almost as good of a job for a lot less time and money up front.