Lots of people like ivory ferrules, especially with higher end cues. I like them because they are easy to clean and look sweet. However, there are several products today that play better, IMO.
Replacing a Predator ferrule with an ivory ferrule defeats the technology of the shaft. The end of the shaft on a Predator shaft is hollow beneath the ferrule for a few inches. This, along with their ferrule technology, is what gives the shaft the low deflection. In order to put an ivory ferrule onto a Predator shaft, you need to insert a dowel/tenon into the hollow area of the shaft, plugging it, then installing the ivory ferrule. You no longer have a low deflection shaft when that is done. I do know several people who have done it and love the way the combination plays, however.
Joe