It's really super-important, I couldn't agree more. I think safety is the first thing that all training courses should focus on and keep coming back all the time. Beauty industry is like a chemical industry in fact, and you need all the possible and impossible protection to stay safe.
Is this a critical flaw in the design of this machine, that renders it considerably less efficient compared to others? And how much the air quality is affected by that provided that regular cleaning of the pre-filters is done? Afaik vapours are not particles, they are essentially molecules, so unless pre-filters are severely clogged they can penetrate easily through them due its molecule-level size. When pre-filters are clogged, they keep letting the air in anyway, it's just that the air pressure and speed drops. I don't have any calculations or other facts to prove this approach is better or worse, and to be honest I didn't expect this whole discussion to turn so technical. However I'm a big fan of facts and informed decisions, and never rely on my own "pure logical" thinking.
Perhaps you checked some other product, because this is exactly what they say (I can share the link if you need it):
The VODEX SalonAIR® 1001 (SA1001) has been specially designed as an extraction system for the beauty and cosmetic industry to extract and remove potentially harmful fumes and airborne dust generated within the salon environment. The SA1001 is an ideal extractor for nail dust.
You can find that all on their website.
This is where Ravair looks more attractive. The filtering device itself is comparable in price with the one of Vodex and it only filters air (no dust capture), however the carbon filter are roughly 3x times cheaper. However, it's not like for like comparison, because the intended usage is different.
The idea of having two separate systems, each one doing one job and doing it right is very appealing to me. Personally, I find it hard to decide which approach is an objective "winner" here. I would say "it depends", but doing either of the two is way way way better than having nothing in place!