What has become the perfect way for me when it comes to controlling a few (or even a lot) of instruments with one MIDI input is to layer them in a single Mainstage patch but separate them with regard to how they are triggered. I might use the breath controller to engage some instruments, that otherwise remain silent, or/and I might separate different instruments with regard to midi note groupings. Here I have the drums reacting to a very limited group of notes for instance. I have two basses here (the HAVE Instruments 'Nordisk Kontrabass' and the AmpleSound Upright Bass) that I sometimes engage or disengage via their mute buttons. In a live setting, I would, of course, switch these on and of with something like the Keith McMillen Softstep 2, so as not to be depending on accessing the computer. But since this is recorded in workshop mode, I'm happy to do it like this for now. I use the TEControl BBC2 Breathcontroller to control the SWAM alto sax output here. This is just one of many layering models I would use, but I really find this way of working inspiring, since I can shift rather seamlessly between the major components it the sonic output.