Apparently my rather obtuse attempt at musical humor in my previous post caused some confusion - my apologies
Seriously, I also have been curious about tamper surface geometry and its effect on the puck density etc. I think it was HB who thought that a convex tamper might help with the troublesome small diameter single filter baskets of lever machines and I am considering trying it with my Ponte Vecchio Export.
I find dosing a single filter basket very difficult. My present technique is to grind finer than with the double, over dose it about 20% and stop tamping before the tamper hits the ridge on the inside of the basket. It does seem to make for more consistent and better shots, but the puck always hits the shower screen. Hopefully a curved tamper will provide a little more headroom and a less mess to clean up between shots.
Geoffrey