Thumbholds are the most common, the non thumbhold with adjustable cheek is next and it is a distant second, the one you just posted is extremely scarce, one sold for $4000 before the recession! The beech one I have never seen a photograph of but a line drawing and good description was published in a ARH catalog I had. It may have gone with my guns but will check.
Have been busy designing houses again and at 72 with one good leg and eye I am not as fast!!!LOL I still laugh at the comment about John Wayne, I believe in "The Shootist" about being a "One eyed fat man" as gun fighter!