Personally, I would never press hand-sewn seams open. There are gaps in a hand-sewn seam, whereas there are not gaps in a machine-sewn seam. When you press to the side, you are covering the gaps in the seam, which is why this practice developed in the first place. I think hand-sewn seams pressed open would almost certainly result in batting coming out. Plus, you don't really have a ditch to stitch in if you open seams. For hand quilting, you'd want to stitch on the side without the seam allowance. Yes, it is a real pain to hand quilt through seam allowances, which is why I try to avoid it whenever possible. This is one of the reasons why quilting designs for a hand quilted piece will be very different from designs for a machine quilted piece. Seam allowances don't have to be avoided when machine quilting.