Good pictures, Silver. I always forget about the index finger on top down here - though I used it ocassionally with light rods up north.
Seems the smallest rod on the boat when I'm trying to help people with their casting is a 10 wt - but usually an 11 or 12.
I will try the thumb on top with the 12 next time I'm casting it. That should definitely help stop the floppy wrist syndrome if I can get them to stop their arms when their hand gets around their ears.