Back to the original Q again, I use both AIO and SG on the black trim of many of our vehicles. It's all I've ever used on the MPV's trim, and also that of the WRX before it. I do w-o-w-o the SG when using it on trim though. I'm not a big fan of the w-o-w-o method, but it seems to give a more uniform appearance on the plastic and the durability seems OK.
I apply AIO with a polishing pad. The paint condition doesn't really enter into it since the AIO won't do any correction anyhow (at least it never has for me). I too apply SG by hand. So thin I can't see it on the paint; I could never get it that thin by PC.