I agree with both you guys; mine is a pin type and that stops me from using it sometimes when I should! I just hate to put holes in a planed surface.
In theory at least you'd think you'd be able to come up with a meter that has cables allowing a user to check the continuity/resistance right through the thickness of a piece of wood, ie front to back(?).
Wouldn't that be more accurate than across the face side? Also, for more accuracy, one would need a sample of the specific species of wood, dried of course, as a reference reading.
My gut feeling, having used mine for years to determine 'condo rot' issues, is that they're just an indicator. They seem to be more accurate at the lower end of the scale.