The company i use to work for switched to milling weld preps on a large 50 taper bridge mill.
Firstly you can't have some one running a grinder over here under health and safety law. Hand arm vibration levels.
Secondly the accuracy - Finnish was superb. Practically no post burn clean up We were in high strength steels and cutting haze was a issue. Till then we had done profile burning of weld preps which is slow, but a lot faster - easier than track cutting that much.
Third and most crucially everything went from a V prep to a J prep. Thats a significant reduction in the number - amount of passes to fill the joint back up on heavier plates. Hence massive welding cost savings as well as a reduction in weld induced stress. Ie products should have a lot longer fatigue life in the field.
I know its not answering your question but its food for thought, a 45 degree bevel is way to wide IMHO for most joints needs.