When he said ‘QC’, that likely doesn’t refer to its accuracy but more so consistency and driver matching. So it’s probably not something you’d use to show deviation/adherence to a target like we do with the GRAS.
In general, stick with GRAS measurements for getting a sense of how the tuning is, because at least with that we have a well established reference point. To be clear, there are reasons why you’d use other rigs - and even in-ear mics - but that always requires qualification beyond simply showing the graph. So in short, it’s not necessarily about what’s better (looking at you 5128), but rather what’s the most useful to us for understanding tonal balance, and that is still the 711 couplers.