Thought I would revive the thread for reasons of confirming thoughts on X-ray bags. I just had a nice face to face conversation with TSA Admin John Pistole. He confirmed the bags are a bad idea because they will slow down the TSA process as despite notions to the contrary, the TSA officer using the scanning machine can not up the power on the machine so it is a form of a red flag. Hand checking is the best way to go if you are willing to wait a bit and personally that has always served me well, just be pleasant and supportive of the job they are doing.
This goes for checked bags too, X-ray bags are totally obsolete at this point, I am surprised they still made...