Two years ago, I experimented with rattles for catfish, I knew that I had caught a lot on lures such as crankbaits, so it made sense that rattles could help attract a bite.
I rigged half my rods with and half without rattles. The rods with rattles out preformed the rods without. And, I had the same bait, rigs, etc. on all of them. However, to cover all the bases, I still usually have 1 or 2 rods rigged without rattles.
One thing I can tell you for sure, the rattles never hurt, and sometimes they help. I let the rattle sit directly on top of the hook, nothing fancy. Just the standard rattles from Hookers Terminal Tackle. I only use them drift fishing. I see no advantage to using them anchored unless you have a lot of current.
