Ian, to your post #3...
I think present AMA rules state that no more than TWO line clips per line are allowable.
Yes, I know, when I was also much younger, we played with additional clips to try to set neutral where our hand preferred. If I recall AMA "guidelines" correctly, that is no longer our option...
To Bob Z:
As others have mentioned, that type of leadout connection was fairly common, way back then, but, as also mentioned, when we used solid wire - .032 or so - for leadouts.
NOT knocking. If the idea of wedding flexible leadout cables with solid wire snap-clips like yours had occurred to people back then, we'd probably see many more such today.
Some of the International community use something similar, according to posts I've seen in other-nation boards. They work.