After reading this topic and another like it it seems that the local inspector could like using the 10-32 clamp screw or he may not. No one posted and code saying you can't so it will be up to the town your working in I guess.
I also would like to point out not one old work box in my truck has any indication of which hole the ground wire should be installed under.
My opinion is I use the extra 10-32 they give you with the box and toss the extra clamp. I like it and it works.
