I do wish I had a meter to see what dust is floating about and had seen one that seemed to fit the bill and wasn't that expensive. This is it:
https://www.amazon.com/dp/B078ZS8RVL/?c ... _lig_dp_it
It was a recommendation from someone that owns one and I have never really studied what is available. I know this can be an importation subject to people so perhaps we will see more recommendations. I do think I will make sure I get something this year.
For me I like to work outside as that seems the safest and I still wear a dust mask, a better one in warm weather and more comfortable one in cold weather. Thinking back to the adage of something is better then nothing.
While I did not participate directly in some studies on dust control I did read and hear more then a few discussions on the subject directly from the group that was studying the issue. I can't say that much of the "common" thoughts on the subject correlate very well to actual research that was done.
One thing that is more then likely the most important is collecting the dust as close as you can to the source. Festool is very good at that. But like anything else the dust collector that exhausts into the same work space will leak some dust and the exhaust stirs the air so any latent dust can get airborne again.
Dust measurement equipment will only measure what is local to it. A foot away can and often is a total different story. If you have the meter attached to you then it most likely would reflect the dust you are experiencing, setting off somewhere else well that is what it experiences there.
Ceiling cleaners can either help or make things worse. They have to be located at the correct locations. put in the wrong spot they do little good and can in fact just distribute the dust. Location location location.
One very interesting study was on intake, something has to get to within the capture range of the intake, the event horizon so to speak. Dust that is some distance away just doesn't get sucked in. The exhaust on the other side of the coin can move dust many many many times farther away then the intake horizon. You can test this with punk sticks, burn one and see how close you have to get to see the smoke start flowing in, then see how far away you can get and still see the smoke trail still going away.
Anyway this is getting off into never never land so I'll stop here.
As far as the CT26 which model do you have?
Of course I expect you to have checked that the bag to make sure it is mounted correctly and that there are no holes like wise the filter. And it is also likely that you would need to test against the shopvac with new filter and new bag if you are using one. The accumulation of dust provided additional filtering so you need to have both systems with new bags/filters to compare.
Air flow in the Festool is a bit different then most systems and while on some of my shop vacs I can tell when the bag is getting full by waning air flow and suction levels I don't see much of that happening with mine.
As far as noise levels, my shopvac brand is an older 16 gal 6.5 hp model with stainless tank. It uses distributed exhaust which does lower the noise level and it is not depending on how you are located to the machine. On the other shop vac the noise level changes depending on where you are in relation to the machine. The down side of the shopvac is no blower output, but at the cost of less noise I guess that is a good trade off.
In almost all cases the tool is the prime noise maker. With either the auto start or with bluetooth the vac is need to be on only slightly more then the tool so total noise is lowered when using those features.
Ed