That's a delicate matter. I don't know exactly how much information the provinces share. As for the processing in NS, current ones are taking less than a month, although we cannot tell if they are still nominating people or just starting the checking processes in order to give the nominations as soon as 2016 begins.
You must be aware, though, that you might end empty-handed. While your NS application is still considered an EOI, the NB one is already a formal application, since they have given you the AOR. Therefore, you can expect them to have assigned a case number, and they may share information about it with NS. In the moment you confirm your acceptance of NS nomination, you will have officially applied to the province. Do you see where this may lead? Even if it is not considered a misrepresentation, because you have probably stated in NS application form that you haven't applied to any other province. You might argue that, by the time of your application, you hadn't, but they are explicit that you are responsible for keeping your information up-to-date. Therefore, by keeping the fact of your NB application to yourself, you have actually failed to inform NS about an important change in your situation. As a matter of fact, they must have asked you explicitly if you have applied to another province...
My advice is to stick to your NB application, which is the only considered official. Of course I cannot deny that this is also best to my own interests, as you are in front of me in NS's queue. And there is also the possibility of your NB be rejected, but if you have any reason to be rejected by them, it is also likely that the same will happen with NSOI. You must understand that this decision is yours alone, as both paths have inherent risks. To help you further, it would be interesting if you tell us how did you apply to NB (through an information session, by a connection to the province, etc) and if they have any reason to reject your connection to their province. Also, as I can see on the SS, you have quoted your Visa Office's location as Halifax. Does that mean that you're currently living in NS with a temporary visa? If that's true, it might have been a mistake applying to NB, as it would complicate your situation with both provinces.
Try also to consult the people in NB's thread, to know how long their application took to be finished and also if it's common to get a rejection after having your case accessed.