From what I have seen bouncing around and watching parts of the SEC/ACC Challenge, the refs are having a real problem with the new hand check rule. In each of the games this evening, they are allowing an awful lot of contact and are not calling fouls when a defensive player has both hands on the offensive player at the same time. Personally, when I read the new rule I thought it was going to cause a problem in the game to game application and, so far, it seems, at least to me, that I was correct.
Adding: In the LSU-Duke game, they are letting LSU get away with, in my opinion, some particularly hard contact, both with hands and body contact which knocks the Duke players off-stride. As I understand the rule, more contact is allowed than previously, but not contact that impedes the opposing player's movement.
Jim