I thought I would just check my email before going to bed. I've got an interesting conversation going on about a particular butterfly, but there you were and I even thought I took cutting edge's advice and unsubscribed from this thread.
You asked a good question deserving a response. I would go with the plow. Think of the mouldboard as a lever and the circle drive as a fulcrum. If you spin that blade when it is in contact with the ground, your putting more pressure on the fulcrum and the circle teeth in contact the pinon gear. Up to you but I've had to reseal that gear box and it's a pain. The drive mechanisum might be even worse, (expensive/ time consuming ). When I'm grading forward, sometimes I want to increase the angle of attack. I have a choice of stopping, articulation, circle shift or spinning the mouldboard. If I chose adjusting the mouldboard with the blade rotation, I will slow down while putting down pressure on the end coming to me to assist in moving the opposite end foreward. Circle shift will do the same, but it results in lifting the mouldboard up which you will need to compensate for, (works well for supers though). Articulation changes the angle of attack w/o changing the blade elevation, but it will effect where the windrow is in relation to your rear wheels. If your rear wheels ride up on the windrow, that will screw up your blade contact with the ground, (difficult to compensate for w/o stopping ).
That's what I love about grading. Choices and results. It's up to me. Much of it is feel. Really liked how the old worm drives could give you feedback on down pressure when they were properly adjusted. I operated a Allis Chamers M60 for awhile and other than too small, it was a sweet machine in the feel department. Bench seat helped too. Found a picture of a WABCO 777 I used that was fun, but the leftside blade adjust was a killer. Owner replaced it with a hyd cylinder for comparsion purposes it was good. Never got around to matching the other side. It's still around, but hasn't been worked for years.