I have been using extreme brushes for a couple of years and am generally v happy with them. However, where they fail is scrubbing off insect poo.
On ground floor windows it's not a problem. Scrubbing with your finger nail or a scraper and its gone. Higher up though it just sits there defying your attempts.
I have some old ionic brushes which have fantastic scrubbing power but are heavy in comparison.
Anyone gone back to heavier, scrubbing brushes?