I've seen a bootleg of Velvet Revolver playing with Izzy, essentially the Use Your Illusion line-up plus Weiland and the other guy in VR.
If I had to choose Slash, Duff, Matt and Izzy with a different singer over Axl and the new band then I would pick the latter.
The voice is what carries it, look how Van Halen fared when they got Gary Cherone in!
In essence, I agree. Axl is an integral part of GNR, but that doesn't mean (for me) that Axl on his own
is GNR. We've never known what GNR was gonna be like without izzy (recording and writing songs), but I think Izz, Slash 'n Axl are integral to GNR's classic sound.
What makes the new band GNR is basically Axl and the back catalog, I am still to be sold on the new material.