Hi Profcleaning,If you are cleaning commercially you should only buy uprights that have metal fan blades.Most of the blades in the vacs that are mentioned are plastic, not good.When you vac up a penny, a paper clip it chips the plastic blade and you will notice as the vacuum is suddenly much louder than it was.Your blade is chipped.The replacement of the blade is pricey at often not worth the cost.Trouble is it needs to be replaced.
Windsor vacs or sensors have metal blades they cost more but I have never in 20 years ever had to replace one, ever.Which translates to they were worth the extra money.
Dyson's are great but WAY over-priced! There is no sense in paying that much, when you can buy a Shark for less than HALF the cost. According to my vacuum repair guy, they both break in similar ways - both use cheap plastic parts made in China which are not cheap to replace. However, I have found that the Sharks seldom require repairs, unless you dont clean the filters, etc. After every job, I clean the whole darn machine, including the wheels and the brushes. I do not want to bring someone else's dirt into another house. I clean the filters every single week.I think dyson v8 is the best choice for you if you have a big expense.
If you are not sure you can view my review at: largereviews.com/best-vacuum-stairs