midi program change from logic synced to mainstage. program changes live on midi tracks in logic, which is synced to mainstage. To do this efficiently, you'll have to explore apple scripts. I do this for my live show. I have a button in the mainstage interface (linked to my midi controller) that runs the script. the script shells over to logic, closes the current project, opens the appropriate project, and then shells back over to mainstage. The entire process takes about 3-5 seconds. you'll want to disable core audio for Logic when performing. You can use the same logic session you used to create the backing tracks, but I create separate versions that contain only midi data. Also create a midi bridge ( IAC in audio midi setup ) between Logic and Mainstage. Make sure Mainstage listens for patch changes from this source. Also a good ide if you hold notes out to not immediately silence previous patch in MS.