You are spot on as usual, light is indeed the enemy, whilst I appreciate RA-4 colour paper technology
has come on significantly no real life tests I have ever seen, and I have seen lots, could support RA-4 of any type being more stable ( but its 10 years since I have had access to real data ) in dark storage or on display. One other thing, due to the mineral dyes used in Cibachrome / Ilfochrome when light fading started to happen they faded and very broadly the same rate so you copuld not experience the 'magenta death' that you can see happening on some colour prints ( and indeed on some inkjet inks ).
Just a discussion, and somewhat academic as ILFOCHROME is no more, and I have no axe to grind as they say.
Simon. ILFORD Photo / HARMAN technology Limited