i've 'killed a chub' in that the bearings went on a brand new chub within 6 months. so new bearings etc... but also, when i put a new cog on recently, the threads where definitely a little eaten up. cheap alloy. so i'm just waiting for that day that i tear the cog off of my chub. granted, i don't skid.. but still, constantly slowing down hills puts enough pressure on the cog/threads/hub.

for more info on chubs and bearings, see:
http://www.bikeforums.net/showthread.php?t=41630