Two very good posts by Volokh on state constitutional law, specifically why didn't Missouri rely on the state constitution for its problematic second-guessing of whether executing juveniles is constitutional? He comes up with some possible answers to that one.
I would say generally that Missouri is not a groundbreaker on state constitutional law. There is a tendency in Missouri to say that police power trumps the state constitution - which is obviously incoherent. State con law is not taught at Missouri Law Schools (maybe at wash u, I haven't checked) and is not on the bar exam.
I know, from eugene's post, that the state issues were raised by defendant. I don't know how well they were briefed or argued. Sometimes they just get a footnote or are treated as an afterthought, and too often the court treats them that way too.

1 Thou shalt run no operating system but microsoft.
2.Thou shalt not harm Gate's image.
3. Microsoft is awesome. Thou shalt fear microsoft and tremble with uncertainty and doubt.
4. Thou shalt not copy.
5. Thou shalt not /kill.
6. Honor your fortran and your cobol.
7. Thou shalt not covet thy neighbors unix, nor her mac.
8. Thou shalt not bear false witness against microsoft.
9 Thou shalt not dupe.
10. Patent pending.