User blog comment:CitizenA/Paint.NET silhouette plugin/@comment-24.184.105.92-20130218160257/@comment-5672532-20130221234645

Without 'spoiling' too much - It is extremely helpful if you're editing images in bulk (oh... so much bulk...) and doing minor variational details. Transparent .png files seem to be more efficient specifically for certain situations, and if you are doing detail work beyond the scope of what I've done.

I guess - the long term answers seems to be that both approaches have their values, and you'll probably need to evaluate your own needs/time.