I'm not sure if this explains the varying Sonoma install experiences, but with my MBP6,2, I have noticed that I need these VMM kernel patches to perform clean installations of macOS:
I keep two OC config.plists (one with kernel patches and one without). I use the config.plist with VMM kernel patches when installing macOS and I use the config.plist without VMM kernel patches during normal operation. I leave AMFIPass.kext enabled (with -amfipassbeta boot-arg for Sonoma) and without boot-arg amfi=0x80. I don't need to change anything in my config.plist except to add or remove these VMM kernel patches. I haven't experimented further to determine whether I need only a subset of these three kernel patches.
I keep two OC config.plists (one with kernel patches and one without). I use the config.plist with VMM kernel patches when installing macOS and I use the config.plist without VMM kernel patches during normal operation. I leave AMFIPass.kext enabled (with -amfipassbeta boot-arg for Sonoma) and without boot-arg amfi=0x80. I don't need to change anything in my config.plist except to add or remove these VMM kernel patches. I haven't experimented further to determine whether I need only a subset of these three kernel patches.