I play with an Eastern Grip and I occasionally switch from open stance wiper finishes around my waist to the classic over the shoulder finish. I usually only use the wiper motion when i get a short ball and I want to make an aggressive approach with enough topspin to keep it in the court. It also helps to modify your eastern grip a bit toward the SW side. Overall there is nothing wrong with the windshield wiper form, but I think the way the face of the racquet is aligned with a "true" eastern grip, if that is what you use, it will more naturally finish over your shoulder. Of course there are always situations where one cannot achieve this follow through or it would be unreasonable to try, and in those cases the windshield wiper finish would be more beneficial. If you can consistently make clean contact with the ball with the wiper finish and do not constantly feel buzzing vibrations from the racquet go through your arm, your elbow should be okay, proper form will dictate how your elbow will turn out.