Thanks for the response bodde.. Yeah I've had a play around with the Diatonic Algo but it still sounds a bit 'fake'
Did you try my settings? You have to know how to set up the diatonic harmonizer for that specific song. I am convinced he double tracked that guitar in the studio. A harmonizer never sounds as natural as a double tracked guitar.
Also it is important where you place the harmonizer in your effect chain; before the distortion or after, in the fx loop of your amp or not. All options have different sounds which can have different uses. For some sounds I prefer it before the distortion for others after.
So before dissing the H9 harmonizer you might want to experiment some more.