I don't think I can add too much to the discussion that hasn't already been posted (too late the hero, but I did start this set in 1997
But if I were to classify which cards are typically listed as tougher cards into categories I would say , in my opinion:
Overated toughness: Shean and Graham (Cubs), Gray w/Stats, Latham or Leifield "initials" variety, Vaughn SP
Underrated toughness : Wilhelm "suffered", Hobby no stats, Moran stray line, Jimmie Collins, Bill Dahlen SP
Tough but acheivable : Joss, Wallace(both "no cap" versions), Hobby correct, no cin, Wilhelm "suffe ed"
Short Prints: Rowan seems to often be low grade and maybe not as common as the other known SP's, I also agee with Wiltse(one ear) for grade toughness
My opinion on Gray (as the OP started with) isn't very scientific either...I wonder how many T205 Dolly Gray cards are graded without any indication of which version it is? At one point I doubt any one cared...I know I didn't when I started collecting T205.
Another opinion of mine is that many of the T205 collectors prefer this set raw...TPG often kills the grades. I have resigned myself that the remaining cards I still need to have graded will get no higher than 30-40 despite very nice eye appeal. I really like the look of these in SGC holders, but I sometimes feel as though the technical grade of these cards doesn't do them justice...So for my third set (I'm about 1.6 sets down, half graded), I will buy low grade and crack them...not good for the pop reports(so what) but better for me to show them off. A couple hundred slabs takes a lot of room, afterall...