If you are not having a consistently better hook up rate you are either using them incorrectly, using an inferior brand, or the fish are not agressive at all.
1st, the brand I consistently use is the Gamakatsu Octopus Circle. It has an offset and is arguably the best if not only hook out there. I use size 8/0 for big fish and 6/0 for eater size.
Correct use of the hook. 90% of catfishermen that I have observed refuse to let the circle hook do its job. That means keep your cotton pickin hands off the rod and reel until the fish is on. If you can't tell it's on, it ain't. So many times I see guys pick up their rod, fiddle with their line..... and try to assist the hook.... and miss the fish. Typically a fish will bounce it, bounce it, bounce it, then try to drag it in the river. Only when the fish is headed to parts unknown should you react. It is probably the singularly most difficult part of using circles known.
Part II correct use of the hook. Everyone seems to assume that the hook needs to be buried, or hidden, in the bait so the fish doesn't "feel" it.
Before you say that cicles stink, try this. Place the circle in the very corner of the very toughest piece of bait. By very corner, I am talking about no more than a 1/4 to 1/8 inch depth from the edge of the bait. The fish will NOT get all the bait and leave you with a little tab of bait nor will it shy away from the exposed hook. I repeat (This is important) Do not insert the hook too far in the bait or you WILL run the risk of the hook turning in to the bait.
If you miss a fish properly using a circle it is that the fish are light biting which is dicy regardless of hook style. If you are not a lazy catfisherman this is the time to add a stinger hook.
I hope this helps,
Shawn
PS. I have used this method on Channels (deadly) Flatheads (purty darn good) and Blues from 5lbs to 72 lbs (deadly)