I bought the X-11 to replace a Scorpion EXO-400 that was too round on top. It also squeezed uncomfortably just below my cheekbones no matter how much trimming or pad swapping I did. But the biggest issue was the unacceptable noise level, even with earplugs.
I tried an X-11 on locally and it fit perfectly. Reviews and forums indicated it was quiet for a race-type helmet, but noise depends on so many variables - rider height, bike-type, fairings, position – that you can't be sure until you actually ride.
Once on the bike, the Shoei is lightweight and stable - head checks are never an issue. I ride a vintage bike like an old lady, but the few times I've had it over 80, the helmet moves like I’m at a stoplight - no issues there.
Noise is minimal, even with all of the vents wide open. I wouldn't call the X-11 quiet, but it isn't distracting either, which was my main complaint about the Scorpion. Again, this is with earplugs.
Venting is amazing. Pop open either front vent above 25 mph and you feel it immediately. All vents, including the two exhaust vents, are easily accessible when riding and intuitive to operate.
In temps down into the mid-40s, fogging isn't bad. In truly chilly weather - in the 30s – I’m expecting to crack the visor at stoplights and around town, but the visor’s vent/lock tab makes that easy.
I bought the helmet based on fit, but I’ve been pleasantly surprised with its low noise level, excellent stability and outstanding quality - basically, everything about X-11 except the price. If it hadn't been on closeout, I would probably be wearing the cheaper Arai Profile.