As far as I can tell, there will be absolutely no differences between the '12 and '13 other than some changes to stronger plastic and the way the two shroud pieces attach. All of those things will go on a '12 if you want to upgrade. The '13 won't be here until September. Buy it now while you can get it. Besides....Gas Gas kind of screwed up the dealers and distributors with shipping bikes this late. I can absolutely tell you that we would really, really appreciate it if you guys would buy the '12s and help move them out rather than waiting on the '13s.
I have no experience with the Sachs on the '12s but I hear it is pretty good. I can tell you that I think the Zoke/Ohlins is awesome.