By virtue of their electrical properties, tubes generate a special waveform when they're saturated, which is why tube engineering has tremendous tonal advantages over solid state or DSP solutions, particularly for crunch and lead sounds. Tubes enter the saturation zone gradually or softly, which lends tube-driven tone its trademark yet totally unique character.
View post (Pinch Harmonics)
View thread
These type of harmonics should work in most places. Natural harmonics are the ones that you really have to work out the places where they will work. I find the type of strings will affect how easy or hard it is to do a pinch harmonic. Its something that will just get more consistant over time.