What is the right way to vibrate? (generally and in MonoGame WP 8.1)

I assumed this should work, but it did not:

GamePad.SetVibration(PlayerIndex.One, 1f, 1f);

This did work (WP 8.1):

Windows.Phone.Devices.Notification.VibrationDevice.GetDefault().Vibrate(TimeSpan.FromSeconds(period));

I assumed there would be a cross-platform abstraction. Am I using the right one? What is the rule of thumb for this kind of device capabilities?

Thank you!