I am running 3.0
When I say dark I should have clarified, its not the overall tone of the Helix but its the tone and behavior of the Drive/Break up or virtual input, like the input is too dark or something, its almost like the same effect when you take a Mesa Mark series and turn up the bass knob. . Its hard to explain really, it got a little better once I messed with the impendence settings but only a little better.
As for real world amps I have reference to from in person quality experience: 5150, JCM 800, Diezel VH4, Uberschall, Shiva (which no one has gotten that one right), Dual Rec, Soldano (though limited and a while since). These are the ones that from experience I feel need attention in the way the amps distort.
I get what you are saying and you are right that our opinions are subjective but there is still something about the way Helix does amp distortion and Fractal does that aren't in the same league. Its just not close, I notice it most when I go back to the Axe fx from playing the Helix, and when it comes to Native, forget about it.The Line 6 Helix algorithms for amp distortion both pre and power just aren't as realistic as Fractal Audio. I also get what its like to have a vested interest in wanting your gear to stand up, I would LOVE the Helix to be good enough for me to sell my Axe Fx II while I still could get some money out of it, while its sufficient for live use, especially given the floor units convenience when it comes to recording, its just not. I know more than a fair share of Youtubers who highlight both units that privately admit that the while the Helix is great kit, its not on the same level as the Axe Fx.
I am pretty sure by how you worded your original reply you are going to come out swinging but I am not looking a fight, I am just being honest, so anything I am saying that is contrary is with respect. I can speak on this matter as I have the first hand experience with both, and if anything, my bias leans towards the Helix because I WANT it to replace the Axe Fx, and I have owned and still do many L6 pieces of gear since 2001 and on so L6 has a special place in my heart.
The last thing I would say about your take on subjective, math, DSP etc is that by your rationale A.I. music mastering should be as good as if not better than tracks mastered my mastering engineers with training, experience and the right room. I think we can all agree that is not the case.