Well I think there is no performance difference....just a matter of preference on how you wanna setup your SSL.....also the crates is a good option for peeps that don't fully use iTunes.

The two advantages of using crates instead of playlists are:

1. Crates are are drive-aware, in other words, if the drive that a crates songs are on is removed, the crate disappears, also if that drive is connected to another computer running scratch live, the crates will appear on the other computer.

2. Crate contents and names can be edited within scratch live.