There are some good pictures of it. I saw the Flux silver during the launch of the GT a few years back. It is a light silver (think it is an MSO color IIRC). Look at the McLaren GT Launch photos, you should see a few pics of the color. Haven't seen it on a 720s. I do like it, but I also like the silver hues, it is much lighter than SuperNova and some of the other silver/greys... I thought is was a nice color.
Does the car qualify for the McLaren ESC? A vehicle that has been identified by McLaren as having been modified it will never be covered. According to a contact at McLaren North America, there were several dealers allowing modified cars to be sold with warranty. Aside from the rug dance by the offending dealers, there were many cars flagged.