I actually don’t think he has a very good take on preload/spring rate/sag.
It’s almost like he’s recommending to pick whatever spring lets you run almost no preload. First problem with this is he’s suggesting to run less than what the rockshox manual specifies. I wouldn’t really advise disregarding the manual on minimum preload. Especially since coils are already so much softer than air shocks to begin their travel, and because a little initial force helps resist the suspension from moving when pedaling when the shock isn’t locked out but the rider is still climbing.
Also he seems to minimize the importance of sag. Sag is by far one of the most crucial suspension adjustments available. It has a huge effect on traction and cornering. I prioritize sag first, while ensuring I don’t have excessive preload.
I’m also not convinced of his take that the rider can just compensate for bike imbalances by adjusting their riding position. I’d rather have a balanced bike with more than a half turn preload than need to ride way over the bars and deal with an under steering bike.
Like everything imo it’s about balance, but mostly about sag
That said, I wouldn’t hesitate to try multiple spring rates. I’ve tried 3 sprint rates on my dirt bikes so far. I ended up settling on the softest one, which btw doesn’t result in the least preload, but gives me what I want.