Had my brand new 2018 212X on the water today for the very first time. 0.1 hours on the engines when she hit the water. Went through the recommended engine break in process from the manual (idling around for 0.1 hours, below 5K rpm for 30 minutes, below 6K until past 1.5 total hours). The max mph showed 52 mph on the trip meter, presumably from whatever factory shakedown they do.
Anyway, 4 adults on board, Bimini furled, elevation 440 feet, ambient 77 degrees, estimated 5 mph headwind, calm conditions, 70% fuel. Only modification was Lateral Thrusters--ribbons still intact. With about 2 hours on the engines I opened it up. Climbed quickly and steadily to 46 mph, with both engines pushing about 7400 rpm.
Had two adults ("the wives") riding in the bow area, and they were having such a good time that I couldn't bring myself to ask them to move to the center to see if I could get a little more out of it. But overall, given the relatively warm temperatures, the weight and distribution, and an undoubtedly tight motors, I was fine with both the mph and the rpm on day 1. No doubt in my mind that in cooler weather by myself (or with two people) and 10+ hours on the engines, it's easily a 50 mph+ boat. Not sure it will see 55-56 as others have reported, but with denser air on a very calm morning, who knows.
Update: Today, 9/9/18, back out on the same lake, 55% fuel, Bimini open/unfurled, two adults on the boat (including me), 80 degree weather, very light breeze, I saw 48 mph, about 7600 rpm. Might have been a nice day to drop the wife off at the dock, furl the Bimini and try a solo run, but we were having too much fun to experiment.