Yes, when the button is released, AF stops. So my keeping the mode in AF-C, you have the choice of the Single Servo action or Continuous AF based on whether you tap the button or hold it down. For focus and recompose it is very handy. Adding the AE-L function to Fn button allows full control of both start and stop of focusing and metering and shuter release become solely releasing the shutter. Once you get used to it, you will not go back. It will be second nature within 25-50 frames.
Stan
St Petersburg Russia

Visit my Nikonians gallery.