I will go against what most others are saying and vote for custom makers cue the way it was made with a maple shaft. Especially if a maker is known for making cues with a specific "hit". If you are purchasing a cue from a maker for their hit, then putting a predator shaft will defeat that purpose. Basically you will have a custom butt that has the hit of a predator shaft.
But if what you are looking for is just a customized balance point, length, certain woods or a certain design; Then go right ahead and order a custom made butt with a predator shaft.
But my advice is to purchase a standard shaft from the maker ALONG with the matching predator shaft. If you ever decide to sell the custom cue, I dont think there will be as many buyers without an original maple shaft. In otherwords, you may just be reselling a custom butt.
Just some of my thoughts on the subject.