My first mysore practice of the Confluence was a bit unnerving. At the suggestion of my regular teachers back home, my normal practice includes a series of prep postures before Supta Kurmasana to work on opening and relaxing the hips. I guess the idea is similar to using props for assistance, with the understanding that the prep postures will be taken away as things improve. Anyway, as I was coaxing my left leg behind my head while seated, a senior teacher came over and began adjusting me as though I were going into Eka Pada Sirsasana, which cause quite a bit of discomfort and alarm. I came out of it and tried to explain what I was doing, but I was firmly scolded for inserting preps and I felt my cheeks turn red with embarrassment.
I stewed over this for a couple of hours until the first afternoon panel discussion, when the senior teachers discussed Ashtanga as a "work in progress". The series of Ashtanga have been tinkered with since the senior teachers had first learned them (some changes summarized by Claudia here), including the asanas, order of asanas, breath count, removal of full vinyasas, etc. Although Guruji always maintained that he taught exactly as his guru had taught him, it is clear that things were being modified with time, and depending on the student at hand. When Nancy Gilgoff asked him why certain changes had been made, he simply responded, "Research."
When Guruji instructed them all to "teach as I taught you," it represents a particular viewpoint from a particular point in time, filtered through the perceptions and experiences of the student (now the teachers). During the panel discussion, they emphasized that the practice, as a whole, had not been modified that much and that we need to respect the series as they had been constructed, but not take it as hard dogma. Maybe this, in part, helps to explain some of the philosophical differences between the teachers, or acceptable modifications of the practice - such as David Swenson's Ashtanga "short forms", Tim Miller's acceptance of props (see that one Vanity Fair article), or my senior teacher's temporary encouragement of my prep postures.