I think you are attempting to compare amplifiers and designers with very different aims. First, Self is a professional, commercial designer of top notch professional audio gear. He made a name as a designer of first-rate mixing consoles where issues of noise and distortion must be minimised at all cost. In recent times, he advised that he is able to design for max. 0.0005% power amplifier THD which is incredibly good for relatively simple, Blameless type amplifiers. He doesn't consider "sound quality" as a valid aim for amplifier design - it's all about zero distortion = perfect audio for most engineers in fact. All his articles and books refer to measurements and perhaps simulation when theory is discussed - nothing written is assessed by ear unless it's just a personal comment.
If we want to hear nice musical effects, they should be added in a preamp style sound effect box with a "niceness knob" in his words.
Rod Elliott's ESP designs are certainly low distortion but as a priority, they are intended to sound good in their intended home use. The two aims may seem to be the same but in reality, as DIY builds, Blameless designs couldn't sound more different.
You may simulate 0.002% for P3a but Rod measures it at typically 0.04% from 1-80W.
I measured it with a QA400 soundcard at 0.05-0.06% from 1W to 50W. That's in fair agreement and what I would expect for the design, typical parts and assembly on matrix board that I used, which was nowhere near as good as Rod's current PCB. That's at least 20 times the distortion of the Blameless designs.
Does it matter that P3a distortion is higher than possible with ultra-low distortion designs? Absolutely! Sound quality is mostly about Hiraga's preferred spread of distortion products or 'harmonic profile', hence zero distortion translates to virtual zero sound quality, in blunt terms.
I'm not going to answer all queries because Self detailed his findings very well and once again, his aim was to determine where lowest THD occurred. I think his results speak for themselves but others have different aims and will persist with higher THD for various reasons, principally for sound quality but also because DIY traditions and reliability in home applications may be just as important to them.