Never seen a robotic disc on a shelf in Walmart? Oh my goodness. That surprises me given that you can get almost any kind of machine in the states.
I have no idea how robotic vacuums clean carpets in general BUT I have seen them in use in other homes. To my eyes they seem to leave carpets looking clean enough and do the job as designed.
As for air watts? We all know its a Dyson fad word. But to keep you entertained, here we go - info taken online.
For a cordless vacuum I would expect pretty low - lower than any mains corded dirty vacumm or clean air vacuum infact.
From what I read online some brands like Neato and Roomba robotic discs offer 30 Air watts. Miele's Scout RX offers 22 Air Watts.
The Bosch Athlet cordless stick vacuum released last year in Europe offers 40 Air watts.
The Vax Cordless Air offers 21 Air Watts (same as Hoover Air Cordless)
Dyson Hand Held DC35 60 Air Watts
Suction, Im sure you will agree is not the be all and end all.
Having had the Bosch Athlet for a short time, I was impressed with its power, but the pick up on the Vax Cordless Air is better as a cordless upright vacuum in my experience - based solely on its triple dust channel Windtunnel design. Suction through the hose is minimal, which is probably how its low air watts test was conducted.
Plus, lets face it - whilst robotic vacuums for the moment exist in cordless discs for the moment, it won't be that long that other designs may well start to come onto the market.
My point is, that we should be having lots of different robotic vacuums NOW.
When you consider that electric cars have been around since 1995/7, technology may well be moving fast in most things, but not everything.