I believe the answer is that not all user exits in the old transaction will be called in the new transaction. In most cases they will, but some may no longer be relevant.
The simple way to check is to put a session breakpoint in each user exit and try processing through the new and old versions of the transaction to see where the code stops.
Even if the exit is still called, then it may be called in a different sequence / timing. For example - exits called on the first screen of FB01 may still be called in FB60, but the header data is integrated into the single enjoy screen as multiple tabs - so check the timing of the call.
Andrew
