Upload & Sell: On
Actually, I get quite an amount of light from my 3 degree grids at both 800 and 400Ws. As for you never having seen them: they were made by Speedotron, and are rather rare today.
I photograph tabletop sets, and I'm most interested in the ability to narrow the beam to suit my subject matter. Sometimes, I'm shooting rather small objects. Other times, I only want a small essence of light in the scene, whether it's highlighting the subject, foreground, middle, or background. The ability to use this to stack grids has much appeal to me and my shooting style.
As for light loss, well, I have 4800Ws of power at my disposal to compensate in my favor.
If you have a moment, visit my site for a better idea of my work.