Glyn, why don't you bring out a 4 section omnipole that extends to 17 or 18 feet and has a short closed length suitable for downstairs. This could compete with the 17 foot xtell poles which seem to sell loads.
Although more expensive, if it lasts for years it could be a great investment for us window cleaners. If you fit one of your brushes (similar to tucker) on an adjustable plastic angle (the sort that is standard on most poles) it could be a great piece of kit.