First photo is with my M6, 2nd two photos are with M8. Both are using the same 35/1.4 pre-asph lux at f8, and both are at 1/30th. Both are on the stationary tripod (note that the M8 has tripod threads under the center, M6 has tripod mount on side).
Focus for the first two images is on the "Scotch" tape wording on the tape on the white comforter, 6 feet away.
Focus for the 3rd image, or 2nd M8 image, focus barrel was moved exactly 1 stop on the DOF markings towards wider open, further focus of about 7 ft.
This author found no improved benefits for the DOF barrel move, to match the DOF of the film image.
Conclusion? Internet Myth Busted. Leica is correct in that no lens adjustment is needed with 35mm M-mount lens on the M8, in order to equal DOF of M FF systems.
Results are here