Um, we don't sit fulltime looking at this site...
Personally I don't think it's necessary to unlock for changing passport, other people think it is better to do so for background checks. I got a new passport after filling in what was then the DS230 and didn't send an update, no problem. But for some countries where background checks can be more detailed it might be more important. Your call.
Thanks a lot for your reply, it's really helpful