Just one other thought. Every new generation model seems to always go through growing pains, recalls, limiited aftermarket support, whatever. If you went for a different, well established model for now and let the first or second production year for others to sort out, you can still shoot for the 2014 or 15 BMW, and by then, the jury would be back in on the water-cooled 1200GSA, probably get a better price, and likely more after market selection.
Just trying to put a positive spin should the aquisition of a 13 becomecome legthy, more expensive or just more inconvenient.
Good luck, Curt
2013 R1200GS K25 (Camhead) Triple Black
2007 F650GS Dakar
“Life is what happens to you while you're busy making other plans.” ― John Lennon