The Blue Moon S658i canister team I enjoy very much. It has probably the most suction and air flow of any residential machine one can purchase. It is rated at over 140 CFM. The machine is "extremely" quiet and powerful. The filtration with just their standard Super Air Clean filtrete type post filter is excellent. If you need better filtration, one can always add the S-Class HEPA cartridge. I find that this cartridge somewhat reduces the air flow (but not really that much) and like using the standard filtrete type filter that comes in each box of dust bags. Even though I have allergies and asthma, the Super Clean Air filter still works excellent for me, with no reactions after vacuuming. The nice thing with the Miele machines is you have the option to use what you want. They even have a special carbon type filter for removal of pet and other odors from the air stream. I think this filter costs around $30 and the HEPA around $50. Most local dealers that stock the Miele line will charge high end list, so it pays to shop around or on the internet. Their S-Class HEPA filter also comes with (and is part of) a thin carbon pre-filter and seems to work great at odors. The air stream smells so clean from this filter after vacuuming.  
 
The only thing I would like to see changed is the length of the hose. Even though it is 6', I think another foot or two would greatly improve maneuverability... or at least have an option to purchase a longer hose. I contacted the factory on this and they are looking into the matter. It appears I'm not the only one that wants a longer hose. The other thing I noticed is that the hose is a bit stiff, compared to other canisters I've used. I suppose it's because their hose is truly crush resistant, unlike the Kenmore (Panisonic) hoses that can be damaged easily.
 
Even though these subtle nuisances are probably not that important, I find the Miele to be the most user friendly of any canister I ever used along with the most powerful and quiet.