Your comment (quality remains even as you go down the price line) was the main reason to choose the S183 as the backup machine. Knowing that Miele products currently in production are almost never discounted (the company may offer a "special", I think my Monte Verde was a "special" and was maybe $100 below normal price during a promotion, so basically we got the same features as the next higher up model...but retailers' prices never vary from what the company wants), to get a machine formerly sold at $350-400 for "only" $229 was what sealed the deal.
Maybe I am placing too much blind faith in the brand, based on my good experience of eight years with the Monte Verde, but it seems that even their BOL models work well, within the limits of their design. They simply aren't as convenient as TOL models e.g. the direct-connect wand vs. the steel wands where you have to plug in the cord yourself.
I noted on Best Vacuum's site that they sell a model in red for c. $650 that has a direct-connect wand. That model appears to be the "entry level" direct-connect model. Not as convenient as my machine, since it has the rotary dial control for power instead of the foot-operated + and - switches, but 90% of the time I don't change the power, I only change it when vacuuming a small rug laid on top of carpet or tile. It has the same amps as my current model. If my Monte Verde ever blew up, I'd probably replace it with the red model.
As mentioned above, my parents' new Electrolux Ultra Silencer Green from Lowes is amazing for $300. Has a HEPA filter, and all the basic attachments. Suction excellent. There is a powerhead one can buy for it for I think $150, or there is a model that comes with powerhead (Oxygen model, I believe) for $500. For someone who wanted a good machine but not at Miele prices, I'd recommend the Electrolux. However, for those of us with a significant investment in Miele accessories, a replacement at least with a basic power-connect model would be the way to go.
When my parents bought me the Monte Verde, I had just had some serious surgery on my leg, they were worried about me having to stoop, so they wanted me to have the speed control with the foot switch and not a rotary dial. Actually they wanted to buy the higher model with all controls in the handle, but since the Monte Verde was marked $100 off, they stopped there instead of going whole hog. Had the Monte Verde been full price, my vac probably would have been a Blue Moon.
Mom felt that a non-propelled upright would be too hard to use post-operatively and that a cannister would be easier for me to use. This was a surgery for cancer of the leg, the 50% survival odds of which I beat and am here eight years later (with leg intact), but at the time they were frantic....for the first time in memory, there was a situation they could not control. So money was no object, they were trying to make life as easy as possible for me.