I have swapped BB's and the messanger contacts followed although some did not work. I suspect the first time you use the new BB in messenger mode it will send a request to be added to the other user. This may cause some confusion to the receiver. I have noticed the available icon when the old BB is used. This tells me the PINS are not auto swapped with the list. So from what I can tell the new pin is NOT sent on its own when you swap until you try to IM them. I suppose it would be nice to have the BB send an updated PIN when this is done. If they can keep a list of available online users, it should not be that hard to send an auto update of the PIN.