As as user I’d love to be able to send midi data to transpose snap so that I could use this feature as an advanced arpeggiator.
I’m arriving at this post because I haven’t found a way to make the “arpeggiator” work diatonically—ie. scale-based patterns that are context-aware. Eg. If I want a neighbor-note alternation pattern in C major, when I hit C it alternates between C and D (a major 2nd), and when I hit E, it should alternate between E and F (a minor 2nd). Same for F-G and B-C etc. Likewise for all other modes.
But it seems that transpose snap can only lock into one key and scale. Looking at the way arpeggiation works in Vital, I’m not sure this will be possible 
Transpose snap can’t lock into key or scale. It’s not harmonically useful as it’s not scale aware. It doesn’t know when it needs to transpose up and when down. I never use it as it’s broken.
I managed a simplified approach where I can automate the interval of 2-note chords, but that’s it.
Helm’s arpeggiator is so useful; not sure if that feature could work here.