From the Apple push Service (APNS) you won't get response for all the successfully delivered notifications and that is "by design".
Redth (the author of pushSharp) posted a detailed explanation of this : http://redth.info/the-problem-with-apples-push-notification-ser/
So you'll barely never get one response-per-notification-sent anyway, not useful to wait for all answers to stop the service.
And keep in mind that delivering the notification to the provider (android/apple/microsoft) doesn't guarantee you the effective device delivery of the notification anyway...