It's worked tremendously well in our association. We've had games with a single USC on a sideline but I'm not aware of any head coaches being ejected for a second USC. I talked to one wing official who flagged an asst. coach. The head coach turned to the assistant and said, "If you get another flag and get me ejected, you're fired!" That's good stuff!
Behavior from assistant coaches has been much better, although things always get a little more intense in the final weeks of the regular season. Hurricane Matthew forced the NCHSAA to extend the season one week, so we still have two weeks to go. I don't know how it's been statewide but I have asked.
We haven't gone looking for trouble. For example, I've told guys to move away from timeout huddles. So if we hear it 20 yards away, then that's audible enough to be penalized.
Basketball will be interesting as any combination of TWO direct or indirect technical fouls will result in ejection of the head coach.