As JohnK told you earlier solidstate, the measurements are taken independently by the NRC (National Research Council) NOT soundstage, they just publish them. So you spamming links doesn't help your cause, it makes you look like a fool. You have become irrelevant.
The first chart is done with the "Microphone measuring position: between lower tweeter and upper midrange" at the standard 2m back. Well this is the rather small "sweet spot" on the vertical axis for one thing and off axis the exact height is maintained and only two plots for each publish graph. The first at 15 and 30 then second graph at 45, 60 and 75 (ok they took a third reading at 75). Again it's important to note that the mike height was kept "between lower tweeter and upper midrange". I wonder if the standard practice at the NRC is to measure in a design's sweet spot at what ever arbitrary height that is! I wonder what they do with a book shelf? Do they even do vertical off axis readings? You'd think to really test a 3 way properly you'd have to ehh! I'd also like to know why they used two graphs and not just a single graph with coloured plots. Not a single measurement was taken from various heights. Especially above, below and BETWEEN the tweeters. I wonder what the graph would look like if the reading were taken on the vertical plane owhh wait Dannie Ritchie has.
OK what I suggest you guys do is use a PC and get some kinda tone generation software like TTG and send a tone to the tweets and mids and then stand back a meter or two and bob your head up and down and left and right. I can literally hear the phase issues between the woofer and mids this might be harder for you Luddites. A Luddite can EASILY hear the tweeter to tweeter cancellation, combing and artifacts by moving your head up and down between the two tweeters with any source like a friggin TV commercial.
This graph is on the money with my very uncontrolled (I don't have an anechoic chamber) readings.
M80 reading by Danie Ritchie
The deviation with my gear is over 23db !!! SHOCKING
As for the VP150's horizontal off axis deviation goes, it is even worse because it falls right where the human voice sits in the spectra and horizontal off axis performance is very important for a center channel if not critical.
VP150 readings by Danie Ritchie
I wonder why the NRC hasn't tested the VP150? Axiom does publish a freq resp but you had better believe it's dead center on both Axises!