I am all about the data. Absent hard data, I'll take anecdotal. Measurement data is largely hard data to me.
This is great dialog on these lenses. Any improvement is welcomed. And you believe there's ~10% loss as a result? But more than made up for by directing, as I recall? A previous post of yours.
loss is usually posted on manufacture's websites..
I would say an average though is 15%
here's a lens manufacture, check them out
from my testing, you can more then make up the loss using a right lens. but remember, I think there's things at play making a highly efficient panel more then lens'.
let's just say my idea right now involves multiple different lens' angles, and spacing is not even spaced in any way shape or form..