This question was answered by Lux Review.
Backlit panels deliver improved efficacy – plus you can do more with an LED array covering a 600 x 600 square than you can with 2400 of LED tape.
However, it’s possible that in certain scenarios edge-lit can look better or provide a more interesting effect than the backlit alternative.
For example, edge-lit panels can fit where backlit panels can’t. A very shallow recessing facility – perhaps no more than the thickness of plasterboard – might drive a solution that looks better than a surface-mounted alternative.
The LEDs in cheap edge-lit panels can create a halo of brightness around the edges of the square of the panel. Some might consider this a visually interesting design choice, although it can also simply look cheap, as in the examples I have seen on the London Underground.
I have also experimented with adapting side-lit diffusers, by adding downlights, for example, thereby creating an altogether different – and enhanced – lighting effect from a side-lit panel.
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