There are several manufacturers of these Navy peacoat, No names for the 50, - Euro, then to "Brandit" (inferior material) or "Mil-Tec" (sleeves too short, material not so nice) for 59 Euro category, and just the Surplus for 5, - Euro more to around 65 euros - I very clear recommendations in favor of Surplus variant for higher-quality processing and significantly more pleasant fabric, better buttons and an overall significantly wertigeres Sentiment / comfort.
For me, (1.80 M 65 kg) M was full enough, sits like a glove. Am thrilled. You want the "Joppen" almost off not again, so probably you will feel it.
In winter at -2 degrees outside, it is enough to wear a T-shirt underneath and buttoning, it remains warm and pleasant.