i agree with most of what has been said here,but no matter what you use,its enhanced by the person behind it! it can be the best vac in the world,but if you push it round 100 sq mtrs in 10 mins,it wont work,taking time to do the jod well is the key,a sebo will pick huge amounts, on any pass, change the bag, and do it again very slowly,and you will be amazed at what it picks up again,dont rush any pre vacking,
Dave