I have been scared by some of the things you have written about dust
Everyone working in friable ("easily crumbled") materials (e.g. wood, MDF, FR4, Garolite, carbon composite, fiberglass) should be very concerned. MDF and carbon composite are some of the most dangerous materials to CNC.
Machining friable materials generate particles that are similar to Asbestos and can easily be even more dangerous because they are hot and chemically active. Toxic, carcinogenic, and teratogenic properties are quite common. Exotic hardwoods (from equatorial areas) can also contain viruses and microbes that are dangerous.
Air safety is the naughty secret of the CNC machine industry. They are more than happy to sell machines and not tell people of the dangers of machining friable materials. Air safety - and sound safety as well - should be things clearly stated "up front" IMHO.
I am seriously considering a CT26 E system similar to what you have in your pix above. Checking the Festool page I see that the hose diameter on the CT26 is 27mm.
The Festool is one of the best; it's not the cheapest but it's not insanely expensive either - once one consider what it does and how it is rated. The Festool CT series is rated safe by the EPA and EU for cleaning up Asbestos, lead, and other nasties.
Keep in mind that it uses a HEPA filter rated at 0.5 (or better) microns to ensure very little (not quite nothing) dangerous gets past the exhaust. That said, HEPA filters are EXPENSIVE. The best way to avoid going through them like crazy is the use a dust separator (i.e. cyclone) ahead of the HEPA filter protected dust collector. The dust separator can remove 95-99% of the particles before they get to the filter.
The picture of my Festool has an Oneida cyclone on top.
It is much cheaper (to achieve the same air safety) to use a much less expensive dust collector and cyclone and dump the air outside the work area (e.g. outside your house). The downside of this method is NOISE. You and your neighbors will not be happy unless some care is used. An enclosure around the vacuum equipment handles the you part; a muffler the rest. This isn't hard but it is a bit advanced. Since this is such a cheap method, it should always be thought about.
By-the-by, it's very common for the vacuum equipment to make more noise than the CNC machine! This is especially true when the CNC machine is in an enclosure.
If one can go the dump the air outside route, I can discuss the best way to do this. One can trivially use 4 inch tubing and high strength dust collectors; they are cheap. Only at the last moment does one step down to the largest that can fit on your machine (2.5" recommended on small machines).
Particles moving in air generate static. This can cause the particles to clump, start a fire, or even cause an explosion. All of these things have happened at large shops; with small machines the risk is low but still present. The solution is simple - use static dissipative tubing or run a BARE ground wire through the tubing.
The Oneida is made entirely of static dissipative plastic; so is the tubing sold with it. All Festool tubing is static dissipative.
Any time static dissipative tubing is used, a solid ground is necessary. If you don't have one, get a ground/neutral checker and check you outlets. If they aren't correct, have a electrician come and fix them. By-the-by a swapped neutral and ground can be fatal.
Some of the rules for vacuum tubing can be found here:
Yes, the stock Festool machines come with a 27 mm, anti-static hose. That is too small to do a good job for CNC dust collection. Festool sells a 50 mm anti-static tube separately. This is what I use.
The reason is found in the vacuum tubing rules - stay as large as you can for as long as you can (from the dust collector to the dust head).
The Oneida is designed around 2.5" tubing but 50 mm tubing works fine. Another vacuum tubing rule comes into play - don't reduce and then expand then reduce the tubing size.
I leave the 27 mm, anti-static tubing in the CT26 most of the time. I use it when I decouple the Oneida from the CT26 and use the CT26 as a shop vac (with a HEPA filter!).
Here is the part offered at Amazon:
A 4M version is also available.
Review the rule of vacuum tubing. If you can make the tubing shorter, do it! It is easily possible to remove the connector from Festool tubing, trim the tubing and reattach the tubing.