Take a close look at this graph here.

As you can clearly see, the main effect of this modification is in the curve of the initial part of the fork travel.

Cool, huh?

Now, consider where your fork would be in the travel once dynamically sagged during a ride (usually around 20-25% of travel is gone when you just weight the bike, actually positive motion ride characteristics are only the last 2/3 of stroke.)

It appears that this actually doesn’t truly do anything at all. The fork performs the same unless you unweight the fork and move it negatively below sag position. All the subjective ride impressions are just placebo effect.