At first I had the 770, but then returned and the 620 bought because I had determined that I know the 770 for 160 Surcharge is no advantage. The comparison in detail: - The programming logic appears to be identical. (Roomba loves chair legs and sticks in their vicinity like 50% of his time on.) - Brush and cleaning performance are the same (both very good, at least on our tiles, parquet and floor mats / carpets kl.). - A (tiny) small plus get the 770 for the vacuum container with the HEPA filters. - The Virtual Wall of 770 I never used and did not know what. - Optical dirt detection of 770 I feel rather as a disadvantage: With our tiles in terracotta look he has expended partially correct, because he thinks they are dirty. This makes the intense mat cleaning not up for it. - The timer programming makes m. E. only if you have a small apartment with no alternative meaning. I ask him anyway prefer manually and after half an hour again. But it also arises from itself, if he believes that he's done. (With many chair legs he runs too short, with few obstacles rather too long.) - The remote control 770 is not really necessary. - The two additional rear crash sensors 770 are hopefully also not necessary. - The chic black glossy finish of the 770 has one drawback: it scratched very quickly if you put him on the back for cleaning.
Conclusion: Both are very good, highly recommended equipment. The 770 gets by me 1 point deduction for the price / performance ratio and the small imperfections that are no longer expected in this price range.
Addendum after 7 months use on tiles / parquet floor mats and 2: Runs still like at the beginning. Replacement filters or brushes were not yet necessary.
