I rarely SITD, but then I mostly press my seams open and ditching does not work well when seams are pressed open. When I do ditch quilt, it is usually only because I WANT to emphasize the lines of a particular design element, sash or border. I will do it with a walking foot before doing any FMQ. I think it's a personal choice, depending on the design, the combination of fabric & batting you are using, and the amount of quilting you plan to do.