My last few trips I have trolled the Suspending Rattling shap raps versus the regular floating RS shap raps and I seem to catch the same amount of walleyes, but I am catching more cats and small mouth. Now I wouldnt say that 3 trips make a rule, but the guys on the cat pages tell me that cats respond to noise and vibration. I know that bass do as well. The only difference in action seems to be that they troll a little deeper and dont pop out as easy on snags.
But for an extra $.50/rap- the extra fish make it worth it!