The small logo Mesa Rectos are among the first ones ever built, from around 1992 to 1994 I believe, and this includes the Rev C through F boards if I'm not mistaken, then sometime in 1995, they changed to the bigger logo, different knobs, and Rev. G I believe. I may be totally wrong about the time frame, but the small logos are the early rectos, and include the coveted "Pre-500" Dual Rectifiers.
-AJH