Simon, that's a lot of questions you have there. Coupled with the number of answers you already got, I am wondering what exactly you are after. Are you simply trying to find the vac and filter that bests suits you, or are you trying to get into the vac manufacturing business yourself? Because the answers you're looking for seem to go a bit beyond what the average user needs to know.
Simon O said:
Also, is a detailed test report, too much to ask for, where the everyday user (me and a fair few others) is concerned? Presumably it wouldn't be difficult to generate, or is the entire industry driven only by the standards required of it by law?
Welcome to the world of marketing, and a derivative - liability. Any company will tell you their product is the best in the world and all you need to buy. A company will tell you anything you want to hear, as long as they can get away with it. Then to make sure companies don't completely rip you off or endanger your health, the government will set certain standards, and companies will comply to those standards mainly to avoid liability. Nothing else.
Giving out detailed test reports to buyers doesn't fit into that philosophy, because they will only give consumers reason for liability suits if a product doesn't add up. Plenty of real world examples available, for instance the recent Volkswagen emissions scandal.
Simon O said:
In my view the American system is far better and simpler than the European system, which I find confusing and disengenuous
Simpler, yes. A choice between to HEPA or not to HEPA, nothing more. Of course two choices is simpler then 3 or more. But can you fit all real world scenarios into just 2 categories? I doubt it.
Simon O said:
Am I correct in saying all American Festool extractors are fitted with Hepa filters as standard?
NO, not correct. As I have already stated above, you can check the Festool USA website to see which vacs are HEPA and which not. if European non AC extractors size 26 and above take Hepa filters
Simon O said:
And back to my original question - why is that Hepa filters are available in UK for 26 models and bigger, but not Sys, Mini or Midi?
A mere marketing decision. HEPA is for AMERICA, not Europe. Festool decided to try it out over here on their flagship models the 26 and 36 vacs and not their smaller ones. So far, I doubt they're big sellers, costing 3 times as much and offering just a miniscule improvement.
Simon O said:
I'd also be interested in the answers to the questions about the filters themselves, as I couldn't find certain deatils about them online - mainly what they're made from.
Why is that important, from the viewpoint of a user? Seems like a bit of a trade secret to me. I don't know if you've encountered this before, but companies tend not to share all these answers you seek with the public. I am not surprised no Festool representative weighs in on this matter.