Outstanding review!
I just bought the MK3 myself. I had tested it in a size large and found it restrictive. I was concerned that the XL would be too large and have too much material to stuff into my drysuit, but was pleasantly suprised to find it fit very well (just a little bit large in the torso).
Did you find you had to go outside of the Whites sizing chart/recommendation? Is the Large a bit smaller than claimed, or were you just between the size ranges?