Personally, this is how I see this issue...You only need this if you have a multi-level house. In that case, invest in a good HEPA vacuum for each level of your house to save your back and knees. Otherwise, save about $1200 and get an awesome $300ish vacuum.
Or better yet, buy the roomba. I have my doubts about this though.
http://www.sharperimage.com/us/en/ca... uestid=361947