I have a new 2016 M6L in a gorgeous Stardust Black. Only mods so far are Ergon grips, ti Brooks B17 and the plastic left pedal extender Clever Cycles sells.
I might consider a ti seatpost if I ever decide I care enough about the weight of the bike (I don't), but I wouldn't trust carbon. Any material in that major load-bearing area that snaps instead of bending is a recipe for disaster. Steel, ti and aluminum bend.