Those 72s are so squirrelly! I don't think I will ever try to collect them! If it makes you feel any better, I wouldn't have seen the edge ding on the 6 you are referring to (still not sure that I totally do).
I always thought I had a discerning eye, but I am also missing most of what has been said about the diamond cut/tilt/miscut on that 8. Looks like you have two decent cards to me, though I do like the 6 a little better...but you know how I am.