There's nothing in the novels or anywhere else thus far that explains completely the reasons behind the different 1701.
And there are multiple theories on the original fate of the sucked out crew-woman, designer of the Connie, inventor of the actual 3539.9-style stardates, so on and so forth.
Having seen the movie 4 times, I feel that there is ONE subject we haven't discussed in here yet. Onscreen "continuity" goofs. I noticed several myself ^_^ : When we first see Capt. Robau, he has the delta symbol on his uniform. When he sits in his command chair, it's gone, and when he and Kirk, Sr are walking to the lift, it's back! The next was in the hanger bay at SFA. McCoy and Kirk board a shuttle that has the low mounted large nacelles, but when the shuttle is heading for the Enterprise, suddenly they're in the "bus" type with the small nacelles mounted on top. On the Narada, when Kirk's going through the tunnel after Spock "appropriated" his future-self's ship, Kirk is holding a long barreled weapon, which is probably a Romulan disruptor, but when the scene cuts to him aiming at Nero, he has a phaser again. Also on the Narada, when Kirk jumps away from Ayel and barely grabs that platform edge, there's a disruptor on the floor. A second later, Ayel jumps over and the disruptor's gone. After Kirk cleverly dispatches Ayel, we see the disruptor again where Kirk dropped it to grab the ledge and not follow Ayel. Anyone see something I missed?