I have had my Rainbow E2 vacuum cleaner for over 5 years. It is the best vacuum system in the world.
It is the only vacuum that is a certified air purifier and is designed to run 24/7 on a lower speed to purify the air in the home.
The unique difference is the water. All dirt and dust is trapped in a basin of water so that no debris can re-enter the home atmosphere.
The machine is expensive but well worth it. I figured I will save about $4,000 over a period of 15 year by using the Rainbow E2 vacuum over the Electrolux I was using. Buy it you will like it.