First time I've seen this thread when I had access to my fishing records...
We stocked 100 CC in 1 acre in Spring 2003. We didn't fish much the first year and I don't remember catching many cats.
In 2004 we caught 62 cats and removed 36 of them.
In 2005 (so far) we caught 52 cats and removed 11.
We have caught them on earthworms (nightcrawlers are best), liver, catfish tails, Powerbait catfish nuggets, a couple other types of prepared (general panfish type) baits, and several types of artificial lures. It is my belief that some of the remaining CC have been caught multiple times and others not at all. I do not think CC catch rates, when I am targeting them, have decreased over the last two years. My CC are fed regularly and withholding feed seems to increase catfish strikes, as you would presume.
This does not include any experience with older CC much over 5 lbs in weight.