My kids and I fished with the Catalpa worms for about 45 minutes today. We landed two nice CC and had two more big ones break lines (one actually managed to wrap it around a field tile pile on the bottom, a first for our pond). This is maybe double the catfish action I have experienced using almost all other baits (a commercial stink bait was close), so I definitely agree with CWorms for catfish.
We hooked them all about 2 to 3 feet down - typical depth to get CC in our pond. My guess is that Catalpa worms are best at whatever depth the catfish usually are at in a given body of water.