I think the original poster made the best decision. Those saying he should have pulled off immediately and landed ahead can only speak with any authority if they've achieved that in a similar situation.

My canopy opening incident was while winch launching a Grob Astir. It appears from the witness marks that my sweatshirt was caught in the canopy lock, behind my shoulder and thus not visible, so the part of the mechanism I could see was engaged and a push up on the canopy didn't move it. A bump on the ground run pulled my sweatshirt loose and the canopy began to open as I rotated into the climb. RH hinged, so I automatically pushed it closed with my left. By then I'm 50ft into the climb and the thinking begins, starting with "fly the aircraft". By the time I've worked out the next course of action (hang on to canopy, because if it opens and breaks away my elevator might go with it, in which case it's goodnight) I'm at 200 ft and climbing. This is not too much height to land ahead on a 3,000 ft runway *if* (and only if) I can use the airbrakes - with my left hand, which is holding the canopy closed. So I rode the launch to the top.

Then some interesting attitudes while I failed to lock the canopy, followed by some experimenting with the airbrake. As I could use my elbow to modulate it between full and half open I set up for a full airbrake approach to the start of the runway, and used the modulation to land me a safe margin beyond that point. A non-event in the end, like the original poster.

As the commentary in the video says, by the time the pilot had everything under control there was still a land-ahead (actually 30 degree turn to a taxiway) option. But that option had to be flown with the aircraft in an unknown configuration - could he operate all the necessary controls? would 200ft of height be enough time to learn? The problem was a known one, and there was no further danger of the canopy disappearing, so I'm certain the right thing to do was to gain height. I'd have ridden the tow to 2,000 ft, to give me the option of using the parachute if I couldn't make the glider controllable for landing.

And let me stress the elevator again. If the canopy detaches at 50ft and knocks off the tailplane, that's probably not survivable. Hold the damned thing on, and work out a better plan!