I'll go along with that. The Hickory nut and the Pecan are different varieties of course, and the wood, at least around here, is a bit different. Hickory is much harder and more fibrous, at least as far as woodworking is concerned, and look a bit different when finished...both are similar for smoking though. I use Pecan more than Hickory, primarily because I have made use of local sources of Pecan...Hickory is hard to come by here in the central part of the state.
Have you ever used Black Jack Oak? I use it a lot; usually a mixture of Mesquite, Black Jack and Pecan. Don't use fruit woods much, although they are available. They are rather mild in flavor and don't contribute much when you use Mesquite.