The one measure I don't see here is the one NRC of Canada does called "deviation from linearity." It measures the difference of FR in db when the device under test is playing at 70 and 90 db respectively. I think this test is a useful proxy for the dynamic range of the speaker. It could also be expanded to see what the deviation from linearity is when the speaker is playing at, say 80 and 100 db.
The speakers almost always show no change
I posted the F228Be spinorama few posts back, it's a Klippel measurement by Harman. Here it is again.
I think the 228Be should not be so different in bass extension so maybe it would be interesting to overlay it to the F208 ASR spin.
View attachment 62635
Do we know Harman is using the NFS? It's possible they are simply using Klippel measurement equipment, but not necessarily the NFS?