I use a white a extreme they're the muts nuts 
those brushes have too few monofilaments to clean faster than the Aerial brushes
you would have to go over the window more times to be certain to get the same results as the Aerial brush
time is money in this game and that adds up to a lot more brush strokes
What you don't realise though Alex. is that in the "real world" a window has more often than not got to be scrubbed a certain amount of times anyway. It would be great if every window was almost clean to begin with, no bird poo, spiders nests, cobwebs, fly poo etc etc etc. Your "one pass" fantasy doesn't cut it with reality. When a window is in the "ideal" state, an Xtreme brush will also clean in one pass.
The Xtreme brush is truly superb! The best I have ever used in fact (the white one) & I've used some brushes in the last almost 8 years of wfp! Yes. less bristles & less bristles hold less crap!
The Aeriel looks more like a bog brush to me, might be OK for washing vehicles or cladding etc but nothing new or revolutionary by a long shot!
