ummm. let the s**t hit the fan eh?
TBh, as a pro woodworker, I have *some* doubts about Bills claims. However, what cannot be ignored by anyone is that he and he alone has probably done more to raise the issue of dust removal and the related hazzards then anyone else.
When I was the supervisor for a hospital, we had an air sample done. Now I really cannot remember the details, but the air was preety damn good, That was with an old system 30 years old, but checked every year by P&J.
I personally would not go too over the top. Go for the largest/most suitable system you can but certainly if you work with MDF or exotics a very fine filter would be advisable. Like anything, a sense of rationale should be employed.
mark