Unsubscribing from events

I am reposting a question I asked on stackoverflow, hopefully someone can help me on this forum.

(I have read http://forums.xamarin.com/discussion/97/correct-way-to-pop-a-dialogviewcontroller-mine-are-staying-in-memory and http://forums.xamarin.com/discussion/4931/summary-of-current-best-practices-for-event-handlers-and-disposing but I am not sure how to implement the suggestions)

I have been using Events instead of delegates in my MonoTouch project, typically using this pattern (iPhone app using Storyboards):

I call PerformSegue to present a new View Controller, and in PrepareForSegue method, I set the View Controller's properties and subscribe to its events using a lambda expression as such:

public override void PrepareForSegue (UIStoryboardSegue segue, NSObject sender)
{
    if (segue.Identifier.Equals("NextViewControllerSegue")) {
        using (MyNextViewController destinationVC = segue.DestinationViewController as MyNextViewController) {  
            destinationVC.SomeProperty = "some value";
            destinationVC.Cancelled += (s, e) => {
                this.DismissViewController(false, null);
            };
        }
    }
}

(as an aside, I chain these Cancelled events where I need to close a hierarchy of View Controllers - whether this is good or bad is a question for another day)

My question is: I recently discovered that if you don't unsubscribe from an object's events, that object is not Garbage Collected. So I have changed the above code to:

public override void PrepareForSegue (UIStoryboardSegue segue, NSObject sender)
{
    if (segue.Identifier.Equals("NextViewControllerSegue")) {
        using (MyNextViewController destinationVC = segue.DestinationViewController as MyNextViewController) {  
            destinationVC.SomeProperty = "some value";
            destinationVC.Cancelled += Cancel;
        }
    }
}

protected void Cancel (object sender, EventArgs e)
{
    (sender as MyNextViewController).Cancelled -= Cancel;

    this.DismissViewController(false, null);
}

My question is this: is this pattern a good way to go about things? And will approach 2 (unsubscribing from the event in the event delegate) work? I am not sure where else to unsubscribe. Or should I move everything to use a notification pattern instead?

Any tips/suggestions greatly appreciated!