Something else I've been mulling over:
Suppose you had some kind of twist grips mounted towards the center of a bar, and had the brake lines spooled onto these so that when you twisted the grip, you were reeling in an inch or two of brakeline.
It would be difficult/cumbersome to get the full benefit of brakes on handles(because you'd need a wide diameter spool) but you might get a significant improvement in turn rate over the "brakes combined to a single depower line" configuration.
I don't know about other kites, but my only "handled" kite is a JoJo ET 2.5, and it doesn't take much brake pressure/movement at all, to make her whip right back around the way she came.
You could still do the saftey leash dicussed above too.
Eric, I've seen your video and your pictures.
You da Man!! I'm jealous.Except for the temperatures involved, that is