I like the Thunderheads more now that they changed the blade locking system. Was never a fan of the old style or any heads where the blades retention is based upon how tightly your arrow is screwed onto the arrow.
1-1/8" is about average cutting diameter, but I would like to see or know more about the penetration you mentioned.
Again, I simply picked up a pack of the Dead Ringers to test for the group and will be interested to see how they preform. Will let you know more after some real world results.