I've only recently got 8 within the last few months.
It's crazy fun, and really has improved my workflow immensely.
All the little "seeds" I come up with I can now record into various clips into one project and expand on them as I see fit.
(Each scene is essentially a different song.)
But for some reason, it's hard for me to envision actually recording and mixing the final songs in it as opposed to Cubase. (...not that I've actually finished an entire song within the last year anyway
) I just prefer the layout and the way plugins work in Cubase for the "real" stuff.
So I probably wouldn't feel the need to upgrade to 9 right away anyway unless it is something that I can't live w/o