Nice to be quoted ...... but the fact that it's as expensive as it is reflects a number of factors, including the relatively high cost of the screen in the USA where it's made (although it's about 50 USD cheaper there), the fact that it's a 2-piece article with a tad more "engineering" and that it probably works better than most others (although on this point I'm quoting others !).
I guess by ".. 5 times more of it" you mean it presents a much bigger surface area, which some feel is unaesthetic and ruins the "look" of the bike. I can't comment on that. Maybe. Maybe not.
The Aeroflow isn't that well known to be honest. I spoke to 3 BMW dealers, one of which said he'd never seen one, and 2 of which they'd seen one once in a while. That could mean they're very undesirable or maybe that they just don't get sold at £300 a shot.
Any Aeroflow owners out there like to comment ??
Alex B