I guess that's designed to get people to rise?
£s as an absolute are not a deciding factor I buy a bike, but value is something I think about (not keen to pay a huge wedge for something I don't think is worth it just because everyone else will).
I tried both before buying, and had intended to go for the GSA on paper.
But after test rides I decided that the GSA would be more of a fashion statement than anything else (not that I'm adverse to this).
I though the GS was a better bike being slightly lighter and (IMHO) better handling.
I have since had a GSA again for an afternoon, and felt it was significantly slower than my bike (although this might be down to my full Remus system as much as the GSA's extra weight).
The one thing that seems much better on the GSA is the screen - which is why I have bought a kit and will fit it over the winter.
To my mind get the lighter and better handling GS, add the Adventure screen (and winglets if you want), then spend the change on some other nice goodies to make it your own (such as Wilbers suspension or a comfy seat).
Standard GS - not so much a downgrade, more an independent thinking GSer's steed of choice