You have to admit that those arrows would be good fire bombs as well as the suit of scale great in a riot and even the shields would help there. However, the foam weapons would be the give away IMO but now think about it, if LARPing was a more familiar sport, terrorists could use our gear 'under the radar' as it were. These days, people are going a bit over protective. I can't believe we STILL have to take off our shoes at airlines since anything that could be smuggled in via our shoes could also be simply put into our pants pockets.
As for the SCA, the berkeley/rock ridge police dept actually would bring their new officers to a fighter practice. They'd just sit in their cars and look at the freaks, but they made sure that their recruits knew that we were (mostly) harmless.