Ian
I know on the rolls rapide, the economy of only 2 swivel castors, I assume the same on the duo-matic, like the cable storage, it's these details you start to see how production costs were reduced. And the control panel is really thin plastic compared with the aluminium on the rolls.
It's a shame we can't make out the end of the wash drain hose, but I don't think there could be a valve on the end as far as I can see.
Oh and yes I do think the impeller would run at 1450rpm, they would need to as they are much smaller and smoother than the Hoover pulsator.
Mathew