Havelock Wool acoustic panels vs fiberglass/Rockwool

@ditusa 

I am not attempting to reinvent the wheel, just add a little bit of room reflection control to a lively space as safely as possible.  Dennis has his followers, as do many acoustic gurus.  

Seems like a no-brainer.  Six panels for $200 ... Thanks for sharing!

Is there a concern about the rockwool or other insulation being breathed in?  Are you not double covering the panels?  I used white batting and then guilford of Maine for my first reflections.  I can't see any insulation particles making its way through two layers of thick fabric.  What is the concern here?  Should I be concerned as my room probably has hundreds of pounds of insulation in here lol.  The way I understand it, is unless the panels are disturbed or aren't covered, there is no real risk?  I do like the fact that this isn't some synthetic stuff though made in a factory