That would depend on how often each was appropriate for each forum. If the feature were to be added, it would need to be a site option (on or off by default).
I think I prefer the “staff notice” to the standard text that starts a “reply with new topic” topic, but consistency would be good here as it’s nearly the same effect being achieved in either case. At the minute (as I currently understand it) it is inconsistent.
In the meantime - is it possible to add boilerplate text that can be chosen for the “staff notice” or to post edits generally?