Having spent most of my life coming up with new ways to do things and modifying everything in sight, and after six years and over 1,500 hours air time flying paragliders and teaching PG pilots, it only took about five minutes into my first tandem flight with a student to see a number of problems and dangers inherent in passing the controls to my passenger should they wish to try controlling the the paraglider.
From an instructor’s viewpoint, there are a number of advantages of being able to allow your student full control of the glider within limits. Not only can you teach the student in a “real world” environment, letting them feel what effect their input has on the ship above them, but also being there with your student provides a situation where instruction becomes a real-time discussion, instead of a the one way, delayed dictation input of a radio. And from a safety standpoint, the advantages of having a instructor ready at the controls if things were to get dicey should be obvious.
Simply passing toggles to your passenger without the modifications that I outline here simply isn’t practical for a couple reasons... and yet this is what is common in the rest of the world, the resultant position for the student is unnatural and strained even with the Dual Control the position is not perfect. The Dual Control is the only way for the instructor to regain control of the glider if he need’s to.
The solution was so obvious it was difficult to understand why my idea hadn't been produced already.