i had a commercial job this morning that hadnt been cleaned for a long time and tried the black gardiners flocked brush and have to say i prefer the medium mixed black and white brush, i couldnt dig the spiders eggs out as the bristles were too soft and as said above it doesnt glide on windows as well as the other type,ended up swapping brushes half way through so i knew the job got done perfect.
i will use the soft brush again but probably for regular cleans rather than first cleans.