the brush looks heavy and to be fair a pile of over priced dung 
The idea of choosing bristles and layout is an interesting concept but I'm inclined to agree with you. Its too heavy and too expensive. It could be the best cleaning brush in the world, but it will not be that much better than a Gardiner brush for example.
The other option is to buy 3 different brushes from Gardeners, a flocked one, a stiff one and a medium mixed and swap them as you need. With quicklok its easy to do and the overall cost is much less. The brushes are also lighter.
Tony, the op suggested that the climate in Oz is different to ours. I'm not sure how that makes a difference. I read once of the experiences of a window cleaner in Cyprus using wfp. He had to spray each window to cool it first before he could successfully clean it. If he didn't then the water evaporated before it had time to flush the dirt away. I don't see that having a constructor brush would be any different to any other brush in that country. Fan jets may help but that's about it.
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