I ended up getting one, it came yesterday and it fitted fan jets.
I agree with your summary Doc, it glides over the window nicely, it will be good for leaded and georgian windows, it doesn't require as much pressure as the SL DT mono to get the middle bristles to contact the window either.
The brush is as light as my SL DT mono, but it is narrower.
I was the same as you with the scraper, im not sure how its supposed to be used,
If i could change something about it, i would like the bristles to be slightly stiffer, but over all, like the fact that it feels nicer on the glass that a SL mono, it feels a bit like a flocked brush, but being a mono filament i am able to rinse on the glass.
So it crossed between a SL mono and flocked brush, so overall im happy, but i wouldn't have bought one at the price they were when they first came out, the price is still a little high, but a replacement brush on its own is only £25.