I think its significant. With a Flat and Level Left Wrist at Impact, on a Turned Shoulder Plane, the Clubshaft WILL be leaning Forward.
Anytime you see a face on view at impact and the golfer with a flat and level left wrist you can now determine his swing plane. If it's vertical to the ground, elbow plane. Leaning Forward, towards or on the Turned Shoulder Plane.
From a Down the Line View of a Golfer with his clubshaft on the elbow plane and with a level left wrist, now you know that the clubshaft is vertical at impact or else the golfer had an arched left wrist.