I, like all of you I am sure have alot of friends that for some reason keep asking me about if they can switch BB PINS from their old to new BB and in a short answer NO. Every PIN is Unique to each BB created or Born mfg:
Then I finally figured out why they are asking after I myself asked a few of them. They are worried about associating the BBM contacts and losing them going to the new device so here is a bit of advice on keeping you worry free.
Use device switch device wizard in desktop manager if your concerned with your BBM contacts. Switch device wizard will auto update your BBM contacts with your new PIN. That is all there is to it and you will not lose anything in BBM.
Hope this helps you out and now you know the scoop...