I just wanted everyone to be aware of this (if you're not already), because it does potentially have heart-breaking consequences. Basically, I bought the Mad King gear off the gem shop, and just after the end of the event I was swapping gear with a full set of bags, and discovered my Mad King gloves had just disappeared (I've since learned this has happened to others with different gear). I assumed it was a clear-cut enough situation, customer service-wise: I had acquired a set of items that can only be purchased from the cash shop and are non-transferable, and one of the pieces was inexplicably gone (not to mention replacing the set would have no bearing on anything gamewise other than my sense of well-being). Seemed to me that no foul play was evident and the item would be replaced, or removed and my gems refunded. Basically, I was told 'we're not helping you, and if you insist on a gem refund we're going to ban you'. I have never seen something like this in ten years of MMOs, I was pretty deflated that a game I love (I even went out and bought all of GW1 after a week of playing GW2) has this type of thing lurking behind it. I spent way too much money on gems the first two months anyway (I'm a dye freak, a collector, and I suppose a gambling addict to boot), maybe it's for the best that I never touch this software again...
TLDR--- DO NOT SWAP EQUIPPED ITEMS WITH A FULL INVENTORY, and if you do, don't expect anything but a rude, unhelpful, and borderline threatening response from the people who handle ANet's customer service. For me it was just a costume, I would hate for someone to lose a legendary in this manner.
*sigh* Anyway, thanks for reading. Or not.