Frankly, this whole debate sounds like it was a massive waste of time. For all their bickering, the authors, agents and publishers involved seem to agree on one key idea: that in the long-term it actually matters what the "big six" publishers do as far as eBook royalties are concerned.
It doesn't.
Given how technology levels the playing field, and how the book publishing model has rapidly moved away from traditional print & bind distribution via brick & mortar outlets, the "big six" no longer possess an advantage and are not going to remain the "big six" for long.
As far as royalties go, virtually ALL of the start-ups doing the most innovative new work are exactly where the authors want them to be as regards royalties: 50% of net. A partnership.
But a partnership implies mutual risk. Thus the absence of large royalty advances from the emerging paradigm, which AG exec. director Aiken, as well as agents, clearly don't like, and which goes a long way toward explaining their love/hate relationship with the "bix six."