Hi Peter.
I’m not a Mac user, but stage tracks works really well with rtp midi over Wi-Fi on my windows laptop. I embed the prg changes in lyrics, and my software receives the commands over Wi-Fi. This is much better than trying to cope with a rather limited 5m Usb c to printer type cable in to my x air.
I think the idea of having slave and master iPads without any Mac’s or laptops would go down well with users too. So I wish you the best of luck with version 4.
Cheers.