> Most of the parts are pretty easily replaced (genuinely pleasant surprise, as an aside) and the company stocked most replacement parts for a long time - I just checked again and I can still get parts for my model (I-series) incl batteries, wheels, brushes, filters, etc. Which is less than it used to be, but still enough to keep mine rolling around for another 3ish years without any likely problems.
I've never owned or really used a different brand than roomba (I've joked that I've owned 4 roombas, but never purchased a single one...) but I fully agree that the modular nature of their parts replacement is a super welcome thing. The fact that the electrical contacts are all just sprung into each other, and each component is basically designed for near-minimal replacement overlap (not replacing things that are not broken) is something that I would LOVE to be implemented in more things. I always assumed that it was this 'forward thinking' design that a) Likely added a bit to the cost of the brand b) Likely didn't assist with future sales from breakages, etc.
Out of the 4 I've acquired over the years, one has been stripped of parts and discarded. One is relatively in that process, and the other 2 are happily (?) doing the different areas of my house. A few amazon batteries later (Which I originally only charge when I am home and able to check on them, then place faith in 'not burning down the house') and everything is hunky doory.
Also, they have been around so long, there are a boatload of 3d printed replacement parts floating around that can be quite useful if one has a 3d printer.
I've always held them in pretty high regard for repairable tech.