ever heard of Keith Merrow?
Yeah, Don, I did. Not sure if I'm getting the point of your question: Undoubtable the KPA is the King in profiling - of course also in profiling the Axe FX - like KM did for instance. But for example try to build up a metal sound from the ground, take those Liquifire/Crunchlabs PUs and shoot it thru the AXE and thru the KPA: You won't beat the Axe in that trial - but of course you can profile the result perfectly with the KPA.
Or play a heavy lead guitar to a couple of Mesas on the Axe with four 4x12 cabinets - you won't tell me really the KPA is still at the same level?
I'm doing studio work since nearly 30 years now and played quite a bunch of preamps (ADA, TC, H&K, Zoom, Vox, Marshall, KPA, Axe ...) with nearly every type of pick up (except Gretsch).
Therefore I found my rule of thumb:
Clean/Crunch: >>> KPA
Distortion/Heavy: >>> Axe
Jazzies >>> try both and take the best
... and your recordings will be fine!