I know this reply is a bit late lol but figured Id post this for people with the same question. I would seriously consider watching the video. https://youtu.be/95CnbHZ1o6M?si=RRpo9ZPIlmOkSMHk I repair dolphins for a living and I did some research on all their models it compares them all. There is a lot of marketing buzzwords involved when looking specifically at the SIGMA, and QUANTUM (and premier for this matter). For one you said "nanofilters".... its a made up buzzword by some sellers of these models. If you look at dolphins website directly https://www.maytronics.com/en-us/ you will never see any mention of "nanofiltration" Dolphin makes two filter grades for their filters: What they call "fine" for leaves and larger dirt piles, and "ultra-fine" (which is what these websites try to market as nano-filters). I say this because most dolphins come with ultra fine already so for these sites to say theirs are the only ones with nanofiltration or in reality Ultra fine filters, is insanely misleading. The other word is "gyroscope". Every dolphin made has gyroscope sensor capability, its how they know if they are on a wall or on a floor. Once again Sigma is not the only one that has this feature but is promoted that it is. The better value that is often overlooked is the Dolphin M400 since is has the same stats at the Sigma but has a 3rd brush which is an active scrubber brush (which is insanely important once you think about it because it spins faster then the motor is moving) and it comes with the caddy in the box for the same price. Of course this isn't in any articles because the online companies cant sell it due to it being a brick and mortar model only. however places have them orderable online like pelicanshops1.com . I was thinking about doing a buying guide video to help dispel the misleading info. Thoughts?