Most of these are not even enabled by default (Mail and iTunes are not growl-enabled so you need to enable a separate addon to handle them), and are trivial to disable (a checkbox in the Growl preference pane)
If that is your "biggest productivity gain" as an OSX user, I'm sorry to say you're just an idiot.
You can't strive for a higher standard when there is no higher standard to strive for: sometimes, a person is being an idiot and refusing to use the right word is just misplaced political correctness.
Misplaced political correctness? No sir, it's politeness. It's treating other people decently. It's acting like a mature adult rather than an angry, uncultured teenager. Bluntness just for bluntness' sake is what's misplaced in polite conversation.
Most of these are not even enabled by default (Mail and iTunes are not growl-enabled so you need to enable a separate addon to handle them), and are trivial to disable (a checkbox in the Growl preference pane)
If that is your "biggest productivity gain" as an OSX user, I'm sorry to say you're just an idiot.