i've been using a vikan monobut am going back to vikan flagged (i spoke to a lady at vikan once who said "flagged")
I believe a flagged brush makes for less scrubbing as there are effectively more bristle ends on the glass.
if you get a mono and a flagged brush and rub them about on a window, the flagged brush seems to be harder to move about. (more friction, better cleaning per brushing action)
flagged brushes do hold more dirt/bits than a mono brush but if you rinse OFF the glass, this isn't really a problem.
if you rinse ON the glass, I think you are better off with a mono brush
that's my take on it anyway
