Some pros for notifier that come to my mind :
1) Possibility to pass data. This is like a variable but without the
need of polling --> no CPU usage while waiting.
2) They allow to wait for multiple notifications --> possible to
synchronize more than 2 parts of independent code
3) A notifier can be cancelled easily.
4) It is not absolutely necessary to transmit the reference number of
a notifier to the different parts of code. You can use its name.
There is a description of notifiers in
..\examples\general\notifier.llb\Notifier BASICS Part 1.vi
If you only need to synchronize two independent parts of code, then
occurences will do the job very well. But if you need more
functionnality, then occurences are not the way to go.
