179cm, 85.5 inseam and Cannondale Scalpel Team M
For what it's worth, I have approximately the same measurements and race on a Large MTB very comfortably. I was previously racing on mediums and doing okay, but after I saw some race photos showing how contorted I was on those bikes; it convinced me to look into racing a large frame and I've been much happier ever since. Shortening the stem drastically improved handling and flickability of the bike in the tight singletrack here on the U.S. East coast.