What about effectiveness of the vacuuming? That's where Roomba is superior afaik, and the feature is pretty essential since you buy them to clean floors and carpet, not to delight you with the smoothest navigation.
As a former roomba owner, the issue I always had was that it was pretty terrible about coverage. The random walk it did often left large areas vacuumed as it had no sense of where it had and had not vacuumed.