In reply to dan leitch:
I've always taken may hardware onboard (rope normally gets checked in), they normally want to get it out and see it, and sometimes call the boss over, although I've only ever once been made to check it in. On time though the boss did ask (without taking anything out of my bag) if any of the QDs were open loop slings, but they were all DMM mambas for a sport trip so he was cool with it.
The one time I had to check it in I was with easyjet, carying only a set of QDs (aka handcuffs . . .) and a grigri. They put the bag in the hold for free, although I was one of a 40 strong group, some of who got through with 60m ropes and QDs, guess it comes down to who is on security