Music In Os X, Trying to move from 9 toX Options

[gibsonlp]

My music is basic rock.
In OS 9 (on G3 powerbook 400 hz) I used MasterTracks Pro to create MIDI tracks for all the instruments I cannot play. Used a light version of Cubase (limited to 48 tracks) to mix down midi and record audio (usually 4-8 tracks, couple of guitars, piano, harp, vocals, and yes a steel drum).
Looking back I have never used more than 16 audio tracks. Always had plenty of spare processor capacity.
Any suggestions for doing that in OS X? Don't need to make music for movies. Don't need suround.
Do need decent audio recording and good MIDI editor.
Considering - Logig extreme, Cubase, Digital Performer. No demos seem to be available for these! Tried Tracktion - very good except for the MIDI.
Suggetions appreciated!
Why upgrade? Hard drive on old G3 insufficient. Have a bunch of G4's, it seems like i should use their capabilities.
Thanks Arne