I read once that tall narrow bowls were best for flakes, and that short wide bowls were best for cube cuts. EXPERIENCE says that it doesn't matter a whit. The shape of the bore seems to matter, as I have found that in conical bores the tobacco gets stronger as one nears the bottom. Otherwise all the different tobacco I have smoked in all different shapes is too similar an experience to tell. Your results may vary of course. My only suggestion is to have different pipes for different types of blends, so that you don't muddy them up.