How? I've had a roomba for almost 2 years now, and I use it all the time - it runs and cleans our living room and kitchen at least 2-3 times a week. There has been a noticeable reduction in dust present in the house. And that's not even a fancy self-emptying model, just a normal roomba where I have to empty the bin by hand. Why would you stop using one?
Not the parent comment, but I think it depends on the house you have. I find huge american houses with 3-5 rooms are unsuitable, except when you limit the robot to one or two rooms.
My apartment in Europe is suitable for it, as I do not have many rooms, so that it does a decent job on cleaning. I do not use the regular vacuum very often.
On the other hand my old European apartment isn't very suitable as my robot gets stuck on high door thresholds and under radiators. It's great anyway, just can't be left alone as I need to save it every now and then.
Have you found those working? All my friends that have one just end up storing them somewhere never to be used again.