My non-Imm b is still in my old passport. I got the standard letter from the embassy but all immigration did when I next left the country was put stamp/notice linking my old passport (number) to my new one. All stamps since have gone in my new one no problem.
One last question, if you do get a re-entry permit and re-enter within the 90 days, do you get stamped in for another 90 days? And if so, is there a limit on how many times/how many re-entry permits you can have?