Vacuums have come a long way since I was a kid. I can remember my mom vacuuming and seeing dust billow out of the bag even when it wasn't full or torn. I don't know what it takes to be fully hepa compliant, but with a hepa filter and hepa rated bag, I can see no dust come out of our vacuum. I have no doubt its not hepa compliant, but I tend to think most modern vacuums do a much much better job of containing the dust than even those of 10 to 15 years ago.
I just checked it out and the Riccar Brilliance vacuum which I own is gold rated on the carpet and rug institute website.
Shark Rotator and Navigator are silver rated.
I'm surprised to see Dyson won't submit their product to be tested at the carpet and rug institute. I am a long time dyson supporter, having owned one for many many years prior to the riccar, but wonder why they won't undergo testing and get a rating?
Miele isn't there either and I know they make a good vaccum as well. I think in this day and age its hard to find a "bad" vacuum unless you get a red devil or some sub $50 walmart special.