sirena is actually slightly more powerful
First, let me say that both a Rainbow and a Sirena have enough power to clean well. Having said that, the Sirena is slightly more powerful, especially when using the nonelectric hose. One way you can measure the raw power of a vacuum is to attach a turbo brush to it and see how fast it will spin. Granted, this doesn't mean that a vacuum that spins it a bit slower will not be able to clean, but it is an interesting test. The Sirena is able to spin my rug rat turbo brush a bit faster than my Rainbow E2 black. So, the Sirena's raw power is slightly higher. It does use a motor made by the Italian division of Ametek. Both the Rainbow and Sirena spin a turbo brush about as fast as vacuums such as the Electrolux 1205, Compact C6, etc. That's why I said that the cleaning power of these water filtration machines was about 30 or 40 years behind the power of a current model bagged canister. While these tests are interesting, we still need to keep the basic question in mind, does the machine have enough power to remove dirt from the surface being cleaned, and the answer is yes.
Mike