Why are are you going to the trouble of arguing with the results if “you can’t argue with results”?
Some of what you said is factually incorrect: upstrokes and downstrokes will always sound slightly different, and there are specific reasons you may choose one or the other for a given part.
That’s why James Hetfield and many other metal players use downstrokes even on passages that are REALLY fast.
No idea what you’re talking about with the “limitations of a pick” bit, or the the “if you’re going to play hard you should just use your fingers” piece either.
It seems like your not really understanding the concepts that he’s discussing in the video: he’s picking downward so that he can attack the strings aggressively enough to get the sound he’s after without the initial attack of each note going sharp.
Simply putting on heavier strings won’t stop the note from going sharp when you first attack it if you’re playing that hard.
That’s why fingerstyle players like Alex Webster have a similar “bounce the string off the fretboard” technique.
I thought I was pretty clear that I think Nolly gets a great sound, regardless of my subjective feelings about how he gets it. If not, I’ll say it straight out: Nolly has a great sound. I actually really like his tone, much moreso than most modern metal Darkglass-using bassists I’ve heard. If I thought the guy sucked I would come out and say so.
Regarding downpicking, guitar and bass guitar are different animals, in no small part because guitarists are usually playing chords; they are literally striking the strings in a different order on their upstroke. That’s why I threw in a caveat for 8-string players. A better comparison would be to Kirk Hammet; admittedly I don’t spend a lot of time studying Hammet’s right hand technique, but I assume he uses double picking. He can do that easily and still sound good because he’s playing single notes. Similarly, for a bassist not playing chords or an 8/12-string the only difference between their upstroke and downstroke is how they attack the string, and IMO theres’ no good reason a dedicated pick player shouldn’t have an upstroke that is, for any reasonably practical purposes, just as aggressive as their downstroke. There’s just no physical reason for it. I can do it and I don’t think I’m a particularly exceptional player. I suppose it may be the case that you could sit down with a recording of me, study it, and pick out the upstrokes, but no one listening to that recording for the pleasure of listening to music would ever notice. I suppose we’ll have to agree to disagree on that,which is fair enough IMO.
Inccedentally, Scott Ian has claimed to have just as heavy an upstroke on rhythm guitar as his downstroke. I say that more as an interesting bit of trivia than as a serious point though, as IMO James Hetfield’s tone is better than Ian’s. YMMV, of course.
As far as bouncing the strings off the frets go, your comment about Alex Webster gets exactly to my point; if you’re going to get your aggression and physicality from bouncing the string off the frets (a technique I’ve suggested here on TB to fingerstyle players trying to sound more aggressive) then it doesn’t make much sense to me to use a pick. It seems to me you’d be better off using your fingers and be better able to shift gears to slapping or to a softer fingerstyle tone. I’ll admit though, I’m not 100% sure I’m understanding the exact way he’s attacking the string; I hadn’t really viewed my post as a particularly serious critique so I hadn’t been as rigorous about the details as I would have been if I were claiming that the guy sucks. He clearly doesn’t suck, I personally like his tone, so I see no real need to get super serious critiquing him.
I hope my point of view on this is a little bit clearer now.