POG2 vs H9

Probably not, in my limited experience. I've got a couple of H9s and while they can do some similar things they tend struggle to keep up with fast playing with some pitch algos. What they do really well is delayed pitch stuff, lots to play with there. There's no feature like the POG2's attack slider.

The closest algo is Quadravox. It has 4 voices other than the dry one and can be set to -2,-1, +1 and +2 octaves. Or any intervals you like.

This demo is as close as I could find for a comparison; the H9 can do the Pitchfactor algos.

 

That was the dealbreaker for me. In fact, I tend to use the POG2 more for that feature than for all the octave voices!

 

can the pog do diatonic - ie as you move through the scale it changes from minor to major accordingly?

 

No, the Pog only does octaves -2, -1, +1, +2