A couple thoughts upon viewing the Burns/McCullough discussion, a real treat to view:
First, the instability of the gliders and 1903 "Flyer" was intentional. The brothers had corresponded with and respected Lillienthal, even though they had to redo his "pressure" tables, and were deeply affected by his death, due to inadequate weight shift control to overcome aerodynamic upset. So they "control configured" their plane, intending that the craft's pitch control be capable of overcoming any gust upsets. Rightly or wrongly, they overdid it some, probably at least partially due to having learned over three years how to manage the canard with piloting skills. In another part of their notebooks, you find too that their concern with gusts led them to anhedral the wings so that any side gust would press the windward wing down, causing it to turn the plane into the wind, probably in a ground loop, at least closer to the ground and slower, rather than raising the wing and sending it faster downwind in a turn away from the gust.
I think Mr. McCullough mis-spoke when he said that full control was only attained at Huffman's Prairie. The Wrights had spent a year completing 3-axis control at Kitty Hawk (overcoming adverse yaw), and only after developing it, did they take the next step, which was to apply power to the glider. While not fully developed by any means, the 1903 "Flyer" could have flown fully coordinated turns, if that had been their purpose that day and if it had had more power and had chosen to fly in lower winds (they were very conscious of safety and launching advantages of low ground speeds). Because of the instability, as Brett says, catastrophic consequences were possible for any mistake or "upset at higher altitude, but the control was there. We should not get carried away by descriptions of the short distances they flew. These flights were many seconds long into stiff winds, and the fact that gusts did not crash the craft is proof enough that they were able to maintain a course, maneuvering with balanced enough turns to avoid crashing due to side gusts.