I’ve just found the thread that I was thinking of here:
This shows the construction of the 99CRI Basic, this one was faulty. The Basic has side illuminated LEDs but they are fed through what was described as a ‘prism plate’ which turned out to have a manufacturing fault. Given that I think that my CS-Lite uses a similar contruction and I’m getting a similar light output to you, albeit from a much smaller panel, perhaps this is a more efficent way of harnessing the light output. As I said I can leave the CS-Lite on continuously and it doesn’t get hot.
Mind you I have a feeling that the NS ‘Pro’ version uses direct LED illumination but as you say that doesn’t have a fan either.