@d.kevin.mcgrath got my motivation right. I did try running the inline booster fan with the Glowforge fan in place, and it was clear just from the sound that was emitted from the GF fan that it was creating a significant pressure differential. It made a complaining sort of siren whistle sound, not dissimilar to the sound made by a toy siren whistle.
This led me to suspect that removing the GF fan would both clear a significant airflow obstruction (itself) and prevent damage/wear to it. I even considered whether or not the fan itself might turn into a sort of ad-hoc alternator/generator, and send harmful voltage back into the Glowforge? I sincerely doubt that would happen, but I thought it was an amusing idea.
I’m not a fluid dynamics engineer, and can’t explain why the internal fan rated at 182.4 CFM would seem to move so much less air than the 190 CFM inline booster fan I used. Maybe it’s just a trick of my ears, and since the noise from the larger inline fan has a significantly lower pitch than the GF fan, maybe it just seems to my ears like it’s moving more air.
I suspect there is a big difference between a fan attempting to “push” air into a duct (like the GF fan is positioned to do) and having a large, inline booster fan sucking it out more like a vacuum. There is no question (in my mind, at least) that the booster fan creates significantly better airflow, but that seems like something that would require some empirical testing to actually confirm, so take my opinion with a grain of salt!