I had a long talk about this with the owner of my preferred shop. I'm looking to get a John H Daniel custom suit this fall, and we went through all the features, fabrics and grades of tailoring. He seems to believe its better to buy the best fused suit you can buy, then to buy a "half canvassed" suit with a floating chest piece. His reasoning is that the chest piece can move to a position that causes the suit to look horrible when worn. It usually occurs when the pressing has been botched or the jacket is in a suitcase for a long period of time.
Apparently if a jacket is full canvas, like a Samuelsohn or Hickey Freeman, this movement of the chest piece is not a problem. I didn't get in detail enough to have that answered, but I was hoping someone here did. Has anyone heard of this view of floating chest piece's and different levels of canvas?