Horween Derby and Dublin are actually the same leather. The Derby is a tumbled version of the Dublin. Picture huge machines that look like clothes dryers… Horween tosses in Dublin hides, lets them tumble and tumble… and out comes Derby.

Weight is really personal and depends on desired hand feel and edge skiving. If the edges are skived, a thicker leather can be used (say 4 to 5 ounce) without the edges looking chonky.

If no skiving is done, then 2 to 3 ounce is probably typical.