Have a read of the explanation at the top of page 64 in the new Argos catalogue which came out today.
They mention figures of:
Hose length of 6 metres
Wattage 1450
Maximum water pressure max bar 100
Recommended water pressure bar rated 90
More water gives quicker clean 330 litres per hour.
There are many previous threads on this subject
If I was buying again I would probably go for a . A friend has one and thinks its the bees knees.