i don't really prefer one over the other, they both have their own sound and feel and i really do like both. our usual set consists of about 11 songs, and i would say i use the ssII for 6 songs and the thumb for the other 5. it seems like i use the thumb for our heavier tunes and the ones that have more tapping and slapping in them and the ssII for the more lyrical or softer tunes we have, but again, either bass could be used for any song, i guess its just however i'm feeling that night.