This is a great article and with the release of 4.5 as now there are two big benefits.
The “All Songs” Setlist PC numbers can be permanently assigned so that you can create setlist that retain the numbers. This is critical for BNandhelper where you have already assigned a PC number for each song.
By doing this, the setlist you create in GP can take advantage of the predictive loading feature as it can be ordered appropriately without losing the PC numbers.
Bandhelper is an essential element for me and my band and I was looking for a way to integrate with GP and I think they have solved it now.
I use a quite similar setup with OnSong. I had the chance to pick an unlimited version with MIDI in the past when starting the whole thing with MainStage and never changed this when porting everything to GP…