I tried the “project per song” yesterday and I found it a good solution. Loading doesn’t take that much time. Maybe 5 seconds?

And for the loading of the sysex files, the problem was that I was using USB-MIDI-adapter and that didn’t work out. It communicated in some levels with A4 but when I switched to direct USB connection, I could load the kits / sounds etc. easily. Dunno why it didn’t work through the MIDI-connection … Everything was correct but the sounds just didn’t load at all. C6 app started transfer but A4 just said “waiting data” or something.