I don't see the advantage over a regular flat felled seam?
With a flat felled seam you have two rows of stitches carrying the load.
You don't have to pin - there's a ruler on the sewing machine so you can position the edges of the fabric on, say, the 1/2 inch mark, and you'll have the row of stitches precisely placed 1/2 inch from edge.
With canvas, you could have the top piece of fabric 1/2 inch, and the bottom 1/4 inch, fold over the top piece, sew the second row of stitches - then you'de only have to sew through 4 layers of fabric which would be easier in canvas.
But, I don't know, I'm just thinking