Without that toggle it means that you could leak private things (content of SMSes, snippets and senders of email) even though the lockscreen is up, which some people want to avoid. We (in push notifications/poll daemon) were asked to implement this; Ted Gould suggested that unity notifications was where to do this, quite reasonably: if leaking an email sender or snipped was a privacy issue, so is an sms sender/snippet.
Given that context, (4) seems to be what we want. Or we want (2), and another checkbox on that list explicitly for bubbles and such.
Without that toggle it means that you could leak private things (content of SMSes, snippets and senders of email) even though the lockscreen is up, which some people want to avoid. We (in push notifications/poll daemon) were asked to implement this; Ted Gould suggested that unity notifications was where to do this, quite reasonably: if leaking an email sender or snipped was a privacy issue, so is an sms sender/snippet.
Given that context, (4) seems to be what we want. Or we want (2), and another checkbox on that list explicitly for bubbles and such.