I have to disagree with your assesment of the iRobots ability to clean. Ive been using one for 6 months now and wouldnt be without it! (p.s. I dont work or know anyone who works for iRobot!)
Yes, its cleaning compartment is small which is ample when you consider it goes on a full clean daily and therefore each day only picks up a small amount. Ive got a dog and the state of the house has vastly improved as the iRobot is picking up dog hairs each and every day. I have to agree that it doesnt cope well with thin rugs etc but after a slight re-arrange of speaker cables/rugs etc, the Roomba now tackles most of my house without getting into difficulties.
Yes you may need to do a thorough clean once a month or so but inbetween Ive found the Roomba more than up to the task of cleaning both my carpets and hard wood flooring.