John
I think the problem is the fact that you are dealing with two things here. A hardware synth and a VST plugin to control it. If you were to bypass the VST it would be possible to have automation on each MIDI track or even just one that is routed to the hardware synth using MIDI channels to work with the control of different patches.
with respect John, the issue is simply that a VST can only have automation on a single track, an unnecessary limitation...and one which makes any multi channel vst a complete mess for automation... the hardware part is the fact that i can only have one instance of the vst running.