Not sure, but almost any old FEAR exe worked with the updated version, you just seem to forget one important thing:
When replacing the new file with an old crack, you autmatically make the patch useless, as the exe was probably changed due to bugfixes etc.
This way, you could have the same state like before applying the update (course, there are changes inside file archives etc, new sounds, graphics, maps blah).
Main changes are done inside the main exe tho
