I ski in Vermont & I would personally choose the AR7 over the 2012 if I could only have one ski, and those were my 2 choices. My reasoning is, if you are going to have one ski on the east coast, you should probably look to a traditional cambered ski. But it totally depends on your style. If you favor a more buttery, playful ski, spend the majority of time in the park and don't care for stability when charging on groomers, go for the 2012. If you ski top to bottom, trails, park, woods I bet you would have more fun on something like the AR7.
AR7 vs AR6 = pretty similar dimensions and flex. AR7 has the new cap/sidewall construction where the sidewall is underfoot for stability but cap in the tip/tail to reduce weight (think JJ or Alpha1). Basically, the new AR7 is a better AR6 that didn't sacrifice anything.