This is really a question of scale, and use case..

How many items do you expect in a list? If millions, i think gong the decimal route is the obvious one.

If 6 then integers renumbering is the obvious choice.

Also the questions is how the lists or rearranged. If you are using a up and down arrows (moving up or down one slot at a time), the i would use integers then swap with the prev (or next) on move.

Also how often do you commit, if the user can make 250 changes then commit at once, than i say integers with renumbering again...

tl;dr: Need more info.

This is really a question of scale, and use case..

How many items do you expect in a list? If millions, i think gong the decimal route is the obvious one.

If 6 then integers renumbering is the obvious choice. s Also the questions is how the lists or rearranged. If you are using a up and down arrows (moving up or down one slot at a time), the i would use integers then swap with the prev (or next) on move.

Also how often do you commit, if the user can make 250 changes then commit at once, than i say integers with renumbering again...

tl;dr: Need more info.

Edit: "Wish lists" sounds like a lot of small lists (assumption, this may be false).. So I say Integer with renumbering. (Each list contains its own Postion)