I bring my scanner into the US all the time. It always travels in my flight bag which I take on board with me.
I have had my bag searched a couple of times but the David Clarks and the flight computer usually get more attention than the scanner.
I use an earpiece with the scanner if I have a long wait at the gate. I love listening to RT in the US - the relaxed atmosphere might grate on some pilots but I love some of the comments that get thrown back and forth.
One poor F/O's mother got slated in KORD one afternoon!