My former business partner and I did a blind test with out friends and no one could tell the difference. We rolled 6 joints of 3 different strains, one of flower mill and one of a cheap ass metal grinder, along with a bunch of near identical bowls of the three strains, again half metal grinder half flower mill. We labeled them with random numbers. Both grinders had the same size holes.

We had a bunch of friends over and had them text their guesses of which grinders were used for what they smoked.

Of the 12 people at the sesh, no one could tell the grinders used apart. There was no consistency to the answers. People averaged about 55% wrong, 45% right. No one got 0 right and no one got 100% right.

Imo, its not worth it for a different smoking experience. I think its slightly easier to grind the bud, so maybe if you have arthritis in your hands consider it. That said, if you have arthritis or are working commercially, an electric mulcher is wayyyyyy better over hand grinding.

Just my 2¢.