I find having separate MIDI/Audio tracks for a single synth part cumbersome, so for the most part I use simple instrument tracks. However, currently you can only make an instrument track if the VSTi is configured as a single stereo output.
It would be good to be able to make an instrument track out of any two MIDI / Audio tracks assigned to the same synth, as long as the synth's audio output hasn't been used elsewhere.
So if I have a synth with 4 stereo outs (outputs A,B,C,D):
Track 1: Audio Track - input Synth Out A could be combined with Track 2: MIDI track
Track 3: Audio Track - input Synth Out B could be combined with Track 4: MIDI track
Track 5: Audio Track - input Synth Out C could be combined with Track 6: MIDI track
Track 7: Audio Track - input Synth Out D could be combined with Track 8: MIDI track
Alternatively (or even additionally), having synth audio tracks shown in a separate bus-style area would help to make the main tracks less cluttered.
What I had in mind was that when you expand the buses on the track view, there would be two tabs at the bottom: "Bus" and "Synth"
The Bus tab would show the buses as it does now, where as the Synth tab would show the synth output audio tracks. A folder would be automatically created for the corresponding synth in the synth-rack: