LEDs are something I've shown limited interest in as I don't believe they have a place in EMs and SS machines. They have a better fit in DMDs. I'm always interested in new developments in Pinball, and this is a perfect example of using something to improve and enhance the appearance of a machine and also reduce the heat and power. Wotto is right, pictures don't do justice.. I saw Marco's ST TNG and it changed my opinion on the machine. With LEDs is simply looks more "3D". Watching the ball buzz around and the reflection of the LEDs on the ball changes the playing experience. The only way I can describe the visual aspect is that it gives the player a more "3D" experience. Hard to describe, but I really liked it.
I will experiment with LEDs on my CV and ToM - I think these two games will simply look awesome !
I think there is a LOT of trial and error with placement - and I think there is scope for a "standard" for placement for each machine.