My rib is orange and doesn't look faded at all - it's 10 years old and looks great. It does look dirty close up and could do with a clean. I've had it a year, but I think it has been left in the water at sometime looking at the gel coat. The other advantage (like yellow ribs) is that helicopters can see it very well (as can everyone else)
SIB before was grey and years old - still looked very good.
BTW the rib is an avon who use hypalon - I don't know if that makes a difference.
Hope that helps.