Ok. Did a few things.
I purchased a new, higher velocity fan on Amazon. Not sure if this fan is the optimal one, but the one Fred suggested on Amazon is now only available as one used one. Really didn't want to go that route. So instead I purchased a NewAir 3000CFM fan (at least that's what the ad says). I also purchased the variable speed controller that Fred recommended.
Using the Ask This Old House "Building approach", I put it together with duct tape and cardboard. I will actually build a wood enclosure for it later. So, in theory, this should provide more air flow than the Lasko Power Plus original fan that I had purchased.
I've attached a new table with the new "high velocity" fan included. Bottom line, it's performance was identical to the Jet 1000B with the MERV 13 filter on it. Within the margin of error for sure. For a fraction of the cost. So, interesting.
The noise produced from the NewAir fan is definitely more annoying than the Lasko, even at the lowest speed setting. Just produces a more annoying frequency, FWIW.
Now when I put all three air filters on high, the results are great. 3138 CFM, 14.5 air exchanges/hr. It may actually be better. I'm not sure if my starting the test with much higher particle counts makes the numbers look worse. The first 2-3 minutes of all units being on was very, very impressive. The particle counts dropped from 5417 to 2231 in only 2 minutes.
So I'm going to keep the third air cleaner, with it placed next to the wide belt sander. I may actually get a timer to have it run a few times a day for 30 minutes or so. I'd imagine the baseline particle counts should be stellar with that approach, with a minor use of electricity. On high the fan uses 113 watts. On the lowest setting it only draws 77 watts. Which is a lot in my energy efficient house, but still a low number in the greater scheme of things (about $0.03/day).
So, I absolutely agree with Fred, and the Shophacks website that this unit does work very well, and can be built (or "Built") quite inexpensively. But fan selection is important.
Air Filter Flow Characteristics.jpg