Joe, just seeing if I understand what you're describing. It sounds like the split ring only keeps you safe if the item attached to the split ring is what gets pulled, not the lanyard itself. That is, does the main loop of the lanyard have a weak point in the arrangement you describe? It doesn't sound like it.

Edit: Re-reading it today, I realize that I was thinking of a loop you wear around your neck. But your example is more of a leash concept, I believe. So there's no loop that needs to give way.