Hi,
I use a usb 4 slot , multi card reader with my psr 1500.
1 card per slot ( sd, smartmedia, compact flash, memory stick( I think).
I have numerous folders on each of these cards. My styles are sorted out by genre.
I have a card for, styles, songs, registrations & multipads. Saves having everything on the same card.
Best part is I just unplug the reader from the keyboard, plug straight into the computer to do any sorting, & back up.

best wishes
Rikki