My tip for sizing. I had to get a tuxedo for my brother's wedding, so I had to get measurements done. I did not take them myself I went to the local Tux shop and had them take them. I then sent those to AeroStich and got the right suit on the first try.
The other thing I would recommend is try it on with the pads you are going to be using, I added the hip and back protectors, they do take a little room.