Quote:
...it would choke and die...

You'd be surprised.
As for 'build-ups' of dirt and hair, yah, you'll need some power to take care of it.
But the Roomba (or any other robot vac) is designed for 'maintenance' vacuuming.
You might only attack your house once a month and in that time the dogs have left you quite a bit to clean.
Use the Roomba 3 times a week and your monthly 'chore' with the canister vac will be substantially reduced.

The concept of 'maintenance' vacuuming is a new one, I know, but only in this light can arguments for the Roomba be made.
No, it's not an 8 amp upright.
No, it's not a 1.5HP shop vac.
It rolls around while you do something else.
It does that for around $300 (often less).
It has exceptional factory support and a great user network behind it.

Comparing apples with apples is what this review is about. (a bit dated, but, hey, whatever. good intro to robot vacuums)

/off the Roomba soapbox now.
//loves me some slashies.
///...and my Roomba!
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10101311 (20GB- backup empeg)
10101466 (2x60GB, Eutronix/GreenLights Blue) (Stolen!)