When I did Doc mods to my JPW's and when I made my Cube 1 clones, I just used my ears to ascertain the amount of doping to the drivers and the value of the protection capacitors - big green Russian paper in oil thingy's. The size of hand grenades they are. I played around (a lot I must be said) until I had a presentation I liked.
That assumes that the other speakers were measured in the same way using a similar microphone and measuring software, otherwise there will be differences that you can't account for.
I suspect however that the main result of your measurement will be to demonstrate just how wrong the idea that speakers require a flat frequency response is in practice.
If treble is spikey the plot will show where the spikey bits are and a notch filter could be added
Just examples, but you get the idea. I'm not inclined to measure for the sake of it, my earoles tell me wether I need to measure in the first place.
The big 15" sealed boxes haven't really needed measuring, they have no crossover at all, they have been voiced by ear
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