John,
I guess I should add that initially I also flew on the 13" SUL handles until I inadvertently left them on the flying field one evening in the dark. When I replaced them, my "local" shop only had the blast handles and since I did have a Blast I got them.
I fly with a very loose / relaxed grip on the handles,my hands seldom completely close around the grips. Most of the time the top lines are resting on top of my index fingers with my ring and pinkie fingers lightly against the grips, tapping and adjusting the brakes as required. Oh, and I have fairly large hands, so thickness of the handle has not been an issue.
Really, I think it boils down to flyer preference and what the individual feels comfortable working with.
Looking forward to seeing whatever you put together on tutorial videos. I also vote for split screens that show the kite and the hands together.
Hope we can run into each other someday on a flying field! Keep up the good work, and I will be sending in a subscription soon.