For coon smaller is better. Self mutilation is enhanced when the opening below the jaws of the trap is larger. Yes coon vary considerably in their tendency to chew etc. I have found that older males and barren females which are large and not really intimidated by anything in their habitat chew less and many are actually sleeping when I check the line. Females that have had litters and Young of the Year coons tend to be more anxious and chew and fight more from my experience. Yes again to each coon has their own personality.
I have also found that drags and using restraining devices, stakes that flex etc. drags will minimize chewing as will having the coons get to cover.