It's not easy finding something reliable on this topic. Those posts are cropped from a discussion asking what the physical significance of the Planck constant is.

Is he being accurate when he claims that angular momentum is quantised? And is he being accurate when he claims that a Planck constant of zero turns a quantum theory into a classical theory? Because if those two claims are indeed accurate, then that's pretty solid evidence that we're talking about a constant of nature, not a simple length.

I think it's easy to get caught up in the "length" aspect of it, in the same way people talk of the speed of light where actually it's not about light, it's about causality. The speed of light emerges from the speed of causality. Likewise, the Planck length emerges from quantum mechanics.

If I were to guess which Planck length is "correct", I'd say h-bar because it's smaller, and if we can have a "smaller" length than the smallest length, there's a problem with the entire argument right there. If h is right, then h-bar is meaningless, but the math holds up under theoretical scrutiny as best I'm aware, otherwise they wouldn't use h-bar because the theories would break at these "smaller than h" scales.

But I'm speculating hard here. I don't know the significance of the Planck units. It just seems apparent that there is a major significance there.