Question about the core exercises in GB

I have been doing some research into  Dr. Stuart M. McGill 's work. He can be found here: http://www.backfitpro.com/

He talks about the dangers of sit-ups with respect to "flexion movement" vs "flexion moment".  Here's an article that explains it better then I could. http://www.backfitpro.com/documents/Spine-flexion-myths-truths-and-issues.pdf

So, from what I gather, he doesn't recommend exercises like sit-up variations due to the high stress on the spine.  What I notice is that GB is loaded with Sit-up variations.   Instead, he recommends planks and alternative approaches to sit-ups. Things like the ab wheel for example.

Could any experts please shed some light on this?  Thanks 

The spine is meant to both flex and extend. I am all for sparing the spine but I also advocate preparing it. It's unreasonable to try and avoid all spinal flexion. I'd like hear what @Wesley Tan and @Mark Collins have to say on the topic of spine sparing. My physio has explained to me that by both flexing and extending the spine, a lot of the potential damage of spinal flexion is mitigated.

As a professional therapist I would have to disagree wholeheartedly 

As an adult adult athlete almost 40 years old, who started with GST 5 years ago I would also have to wholeheartedly disagree.

Actually, the GB course is extremely well balanced with regards to motion and muscles. Static holds, dynamic movements, stretches, traction, rotations, inversions etc. Research as it stands could never test GST how it is practiced. All these variables would have to be tested individually otherwise it is hard to prove one thing is responsible for another.

I mean, with movements it could as well be the absence of one that leads to a result just as much as the presence of another. Not to mention the complex effects of a system of movements.

Research tests things in isolation that do not occur in isolation in the physical world. Quantum physics has also demonstrated that researchers actually influence the results of experiements depending upon what they think/expect to see (wave-particle duality). I quote this as I firmly believe people will see what they want or in otherwords what their current perspective offers them. Shift your perspective and your views change.

When I was an Osteopathic student I was surrounded by many older academics/therapists who had no idea about how to use their own bodies, yet lectured on how the body works. I do not mean to say I learned nothing from them and that what they tought was incorrect. However, when you want to learn about physical training and preparation you have to learn from one who knows and has done it. Who has the results already? Real living results. 

Take note of what McGill has to say and then just watch as we all progress anyway