Apple are not releasing sales figures for the opening weekend this year so it maybe a while. At best we will get some rough estimates.I haven't been fully keeping track on the thread, but my impression is that most of the Apple-direct preorders posted here that have moved up from 27-29 Sept to 20-22 Sept were either Black or Jet Black, and mostly Plus phones?
We'll likely never know if it was high demand or low supply. I expect that when the un/official figures eventually filter out there'll have been a far bigger ratio of Plus vs Standard orders for the 7 than previously, relative to the 6 & 6S, which you'd expect as people get used to the idea & the dual-cameras may have accelerated this.