Honch, it seems to me that you might be able to do that in the Phaser algo now.  I don't have that algorithm yet, but perhaps using the sample & hold waveform with one of the deeper phaser types.

I did something similar with filters in the PitchFactor's HarPeggiator algo, and it's one of my favorite presets.  I still have my SE-50 here [sadly, no MIDI sync rate].  I'll need to compare that with the H9 offerings to refresh my memory.  I remember a Stereo Flanger effect with Gate on the SE-50, but not the Step Phaser.