I have the pinking blade and I have used mine to trim the edges of my quilt after it has been quilted and the binding has been applied to the front. It is, in my opinion, harder to get an accurate cut. A prolific blogger quilter finishes her quilts in this way and I thought I would try it.
I mostly use mine in non-quilting sewing, though. I think it is a handy tool to have. I had an extra cutter so I bought the blade and I just leave it on so it is ready to go when I want it.