I'm not much sensitized to bit and button size for pipe selection, but I'm learning from this and earlier threads. My sense of it so far, more from a variety of pipes rather than discussion, is that I don't want an oversize button, true, but with heavier pipes -- and I have just a few of those -- a little more button helps keep the pipe in place when you swing your head around or otherwise change positions. A slightly wider stem also helps stabilize a pipe, either a heavier pipe or for clenching. Vulcanite is softer, for sure, but with lighter pipes, acrylic seems fine for me, and certainly sustains its appearance better and requires less maintenance. I have one P-Lip which I enjoy in rotation, but I wouldn't get another. I'm aware of it in a way that is distracting, and redirecting the smoke doesn't seem to have much benefit for me. Nonetheless, I have really enjoyed this thread precisely because this is something I don't ordinarily focus on much. At least, now I will notice and consider this aspect of my pipes.