It should do better than that. I just dropped a wrapper from a cough drop in front of it and it ate it right up. On any given day the BOBSweep is picking up about a cup of cat fur, tracked litter, small pieces of paper or cardboard the guys shredded, dust and lint. My guess is if it's much bigger than a quarter, it's probably not going to get picked up.
This is currently covering roughly a thousand square feet on each floor. Roomba on the second, BOBSweep on the first. While it certainly doesn't replace a regular vacuum we are probably only running it a third of the time we were before we had the robots. In fact with how well the Roomba is doing on the second floor, I'm guessing we might be able to do away with a standard vacuum all together.
With the BOBSweep you can set it to charge and go as opposed to being on a schedule. That will see it run about every 4 hours. Often they are getting to places we don't get to often enough, such as under a sofa or bed and can get the filter clogged early on. Also, at our current residence we are probably only about 40% covered by area rugs on the first floor. I do think the Roomba was superior going over carpeting, but no major issues with either.