I think I'm going to cancel mine. I need to get the ball rolling on requalifying for AA Plat in early 2006...so it's worth it to me to just find a decent fare on OW. Plus I'd still need to get ORD and from MAN to LON, most likely.
I'm always on FlyerTalk and able to price out these "mistake" fares...someday I'll take advantage. Enjoy Manchester, all!