Not sure that it matters, but I was out yesterday afternoon in the LI Sound casting my 11'6" GLX using a short 10-wt. intermediate head looped (via heavy braided mono) to the Airflo non-stretch shooting line. While the head stops abruptly, as you say, the diameter of the shooting line isn't too much smaller than that of the head, and in addition I had reinforced the loop connection on the butt of the head (?) by wrapping it with Uni-Chord and finishing that with Flex-Cement; this made the connection at that end more stiff, and there was little to no hinging. Perhaps the added stiffness in the butt works similarly to the short reverse taper you're thinking about. I may try that idea with a 9-wt. floating head I have.