I've had a Miele S500 series canister for 12 years. Never any problems. I take it in for maintenance once every two years (I guess they lube and clean it, I don't know). Over the years I built up quite a collection of attachments:
1. Long crevice tool. Cleans lint traps and under the frige
2. Long dusting brush. TOps of cabinets/bookcases, ceiling fans etc
3. Long furniture brush: covers twice as much area per sweep vs. standard upholstery brush
4. Micro cleaning set: lots of neat miniature attachments
5. Turbo brush: cleans stairs, car seats, dogs (a now-deceased Rhodesian Ridgeback loved being groomed with the Turbo brush).
The S500 was a gift from a well to do relative. The only cleaning function that is mediocre is cleaning carpets. I have the original 217 power head. They now make an improved 227 or 228 power head with height adjustment, a more vigorous brush action, and a wider sweep. It now comes standard on their higher end models, but to buy just the power head to upgrade my canister would run $225-250.
I felt the money was better spent on a new Miele S7 upright, the most basic of which (no headlight, no HEPA filter---though you can add one, but same motor and feature set) sold for $429---there was a special at our dealers and the price dropped to $299. I figured this was a better value than buying new upgraded power head since for $150 you get a whole new machine, which likely is better at cleaning carpet than even the upgraded power head. The other two advantages are:
1. serves as a back up if the canister is in the shop for repair or maintenance.
2. suction hose accepts all of the attachments I already own
The higher end S7 models have a headlight, come with a HEPA filter, and have some/all of the attachments. For $35 I bought my own HEPA filter, I don't vacuum in the dark so don't need a headlight, and I already own all the attachments, so for me the basic S7 (the blue one) was fine. Someone buying a Miele for the first time might want a higher model to get some of the attachments. My only criticism of the machine is that it's heavy, I have a one story home but I wouldn't want to lug it up the stairs if I had stairs. It also does an excellent job on hard floors: you turn off the brush with a switch on the handle, and it automatically height adjusts. Does not scatter dirt around, it gets hard floors clean. Of course, you can't get it into the tight vertical spaces that a wand can reach, but there is always the option of using the attached hose and a hard floor attachment or the turbo brush (hose/wand is not electric, hence cannot attach power head).
