I got a large to fit over an Alpinestars Tech Air-5 which needed a bit of extra space. It fits well with a bit of stretch so it doesn't feel either too constricting or baggy. This is my cold weather jacket and the leather blocks the wind nicely. You have to tuck the drawstrings on the hood into the jacket to keep them from flailing around, but that's to be expected. It looks great and I wear it out as a regular leather jacket. The only reason I'm giving four instead of five stars is because of the armour. The elbow armour in particular is quite hard and uncomfortable so I replaced it.
I actually ordered a medium and a large since I wasn't sure which would fit. I did have to pay for return shipping for the one I sent back, but FC Moto processed my return even after it took a couple months to get to back Germany (return shipping from Canada was not fast).