I have had my Rainbow D4-SE vacuum for 16 years. Yes, it has been well worth the investment.
It is the best vacuum I have ever had and I have had probably a total of 10 vacuums over the past 25 years and many years ago cleaned houses for a living so I have used just about every brand there is.
I have one Malamute and one Siberian Husky, so the hair is almost impossible to keep vacuumed up.
Last year my power head on my Rainbow finally gave out after almost 7 years with my Malamute’s hair. In the past year I have purchased a Dyson (a dream to empty), which lasted all of three months and then quit working for floors and I could not find any shop that would repair it, they all wanted to sell me another vacuum for more than I paid for the Dyson!!!
I then purchased a bagless Hoover Mach 5 for less than $200.00, which works okay, but is a nightmare to empty (the Dyson works very well for vacuuming out the cyclonic chamber on the Mach 5 though, if you can afford to spend the money to buy a vacuum to clean out your other vacuum).
As I said before, the Rainbow is the best vacuum on the market and well worth the money since you will have it for years. I still bring my Rainbow D4-SE out for the bare floors since it is the best and really gets into the corners and under the fridge.
I also use it just to filter the dust out of the air in the house about once a week. (Try doing that with any other vacuum.)
My only problem is trying to find another complete power head for my Rainbow D4-SE at a reasonable price, since I have spent so much on vacuums this past year already.