actually, to elaborate a bit on the flat/convex debate, apparently convex tamps are a bit more forgiving in the cafe's when there's a rush - I guess when you're working quickly, it could be easier to mess up the distribution, or not get it as good as when you're not rushing. The convex base sort of pushes more coffee grinds to the edges of the basket, evening out the distribution a bit from the middle lump that grinders seem to put out. Also, I've noticed that my shower screen and the bottom of my double basket are ever so slightly convex, so in theory, a slightly convex tamp would match the screen and basket, creating a more even puck ... in conformity ...