I just did a poll about this very topic on a long arm chat site. We discovered many blue ribbon winners now press open. In the past, they pressed to the dark side whenever possible. Now they do what is best for the quilt and reduces bulk.
Our machines, thread and fabrics are so much better and stronger than the handquilting of decades ago, and it's no longer a matter of strength. Quilts all hold up fine either way. Pressing open allows for a flatter quilt, with flatter seam lines, easier piecing/matching and nicer quilting in many respects. There are no quilt police - even though most of us (me included!) were taught we would go to jail if we did anything other than 'press to the dark'. It just doesn't hold true anymore :)
And so, I do whatever is best for the quilt. There are no rules...just myths :) It's all good :)