Does it matter? We are talking about fun consumerist novelties facing a shrinking population with shrinking disposable income. No one needs these "things."
That’s the real issue. As far as I can tell everyone who wants a robot vacuum already has one, and if they’re crappy enough that you’d upgrade, they’re also crappy enough that you’ll likely just give up.
If they work, you’d not feel the pressure to upgrade.
If they work, you’d not feel the pressure to upgrade.