I did a bit of research on new vacuums now that I have a dog that sheds heavily twice per year.  My old (non pet Dyson) vacuum was admittedly 11 years old, but unable to keep my carpets clean enough for my allergies.  I compared numerous new pet vacuums and decided on the Shark Stratos.  It is only a month old, so it should be effective.  I never thought that I would get excited about a vacuum, but wow... I have been 100% impressed with how clean my carpets are, so my expectations have happily been met and exceeded.  The roller still has zero hair on it after a month and the volume of hair / dust / whatever was in the carpet that has been removed and in the canister is scary (in a good way if you like clean floors).  It's also easy to interchange the different cleaning options that it came with, so my stairs are the cleanest they've ever been and my wooden floors are completely clean as well.  Unquestionably a great purchase for allergies and better breathing...!