Well, it depends on how do you like your leather jackets to fit. However the 55j14 is a slim fitting jacket, in the chest, but, it has a more relaxed fit on the shoulders. About the action/bi-swing back and the armpit gussets, the answer is yes, they help a lot with giving you the same mobility and conform as if you were wearing a bigger jacket. My personal advice is to buy it in your true size, no need to size up.Question regarding fit, as I have never tried a G-1: should the pit-to-pit be similar to the pit-to-pit of an A-1? Or do the gussets and/or different armholes allow for a smaller measurement?