> more powerful vacuum cleaners ((as in, more expensive to run)

I know it's not your point, but on top of everything "more powerful" is misleading.

- Typically this means more power consumption, not suction power

- Most modern vaccums improve with cleverer working designs to be better, not by just chucking more power into it

- The majority of houses in the UK have carpet, which makes this kind of vaccums silly, as anyone with a carpet and 2kW vaccum can tell