None of those mentioned John surprise me at all that they may well be fading to one degree or another now.
If you'd have said you had a fading print of Terminator, Aliens, Die Hard, Commando, Mickeys Christmas Carol, A Grand Day Out or Master & Commander or Beauty & The Beast etc etc etc, (the list is endless)..my ears would have pricked up.
But you didn't John,. and as such you missed the essential era of Derann released feature and other shorter releases which are all on low fade stock from 85 onwards, with no fade whatsoever at this point in time.
The people you speak with regarding their reasons for collecting Super 8mm film are very different people than those I speak with from both your neck of the woods as well as from here in Europe John.
I hope you don't collect 35mm or 16mm film John if you are a complete stickler for the rules so far as copyright and private ownership rights are concerned.
This is a film enthusiasts forum let's not forget.