Seminar just got over. I was somewhat dissapointed in the amount of time he spent on the most very basic stuff. This was supposed to be advanced tips and tricks, not much of that other than talking about "making" beer from its chemical components. Yuck!
He did comment on HSA, sort of. He said that, compared to the handling of commercial beer post-production, kettle effects are basically neglible. Not sure this answers the question of whether HSA is significant though.
He also took my question about pressurized fermentation. His observation was that this reduces ester production, which can either be good or bad depending on what you are after.