RE: Question about the 400 foot limit.
Remember, an AC is an "Advisory Circular" which is not a FAR (Federal Aviation Regulation), just voluntary guidelines. Of course if RC pilots routinely refuse to follow these guidelines, and cause problems for full scale, you can bet a real FAR or worse will follow.
Back to the OP's post, I would just about guarantee that Master Blasters are working closely with the FAA, ATF, DHS and other local authorities as needed!
Later!