I've just done my mrk 4 in Black (041)
I used a rotary with this combination:
Mez compound pad with Megs #83 then Mez polishing pad with Megs #80. AG SRP by hand and a coat of Megs Mirror Glaze #16.
The paint is really hard and I might by trying out the Mez IP and then the Mez FF on the same pads.
Its not quuite there it needs another go, but I think I am getting a bit anal with this polishing lark
Before (OSR quarter side on door:
After
I am now attacking the deeper scratches with touch up paint, will be posting results up as I finish.