I have a True Religion denim jacket. I am usually between S & M in jackets (I have the broad upper back with big upper arms). I was able to get a Small, but I will only wear it with sleeveless tops under it. That's often my experience with jackets. No real help, but I found they did NOT run large to size.
For a purchase of that magnitude, I would order whatever sizes you are deciding between, try them both, and have to pay return shipping on what doesn't work.
Fortuitous that 6pm.com price today is about $100 less than yesterday'. . . ??
ETA: Today shipping is $2 less than normal. . . boy, did they see you coming Tarzy?