i used a stiff radius sill brush dual trim with very hot water and virosol today for 2 add on jobs.a conny roof clean and a full UPVC clean.its a great robust brush and has excellent scrubbing power but i wouldnt use it for regular window cleaning as for me its too heavy to use day in/day out.
ive got used to using the extreme stiff brushes for maintenance cleans as there so light and still scrub well for a lighter than light brush.coupled with a carbon gooseneck its the only way to work for me.