Good question, Ben.
Seeing how they were first really noticed in the early 2000's they certainly haven't stood out. If you search the threads here, I believe Jay Behrens may have brought an example to light in about 2002 or so and now we've got around 20 or so poses known, a scant few with a couple known copies each. So end of the day, they're pretty high on the difficulty list.
There will shorty be a follow-up post revisiting the T207 backs with a back run discussion thrown in for good measure. Once I'm over the effects of COVID (first timer
)
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Mike