Whatevever we do I am keen that first we explore what can be done from the Octopus itself (I want to manipulate from the octopus as much as possible), such as you descrive above.
My requirements are way simpler, and in effect different from the one of the others (by no means better).
There are two things I want to do, and I’d like them not to get lost in the discussion…
1. To be able to transpose the scale, as Gabriel mentioned in the quoted bit above. ie. what started the thread. (yey! it’s already prototyped).
2. Transpose the page and stay in the same scale.
This is already there, why this is important to me…
If my page is mainly playing in C maj steps, I have a C Maj scale selected when I transpose the page +2 I get Dm (dorian minor), +7 I get G7 and so on and so forth… (Ok this may boring stuff for you, but it’s important for me for improvisation).
At present this can only be done from the Grid, or by selecting all tracks and changing the pitch. It would be nice if this could be done from inside the page maybe by pressing Page and turning Pitch… or whatever..
or maybe even using the MOD but in a different way:
A. doubleclick a scale note => page will transpose (c =0, c# =1, d=2.. g=-5, g#=-4 etc…)
B. single click scale note + scale => scale will transpose. ( alternatively press SCALE (or MOD) + Main Knob and scale will transpose.)
or whatever..
What can I do with this…
well I can play my Cmaj page as C, Am, F, G7 by just doubleclicking on a scale note, I can do C, E, Bb chords by clicking on scale note (root chord I want) and scale I want.
But wait there’s more, I can mix the two. 
This, me thinks, would make me happy plenty!
BTW while we’re here, a way to overwrite preset scales could make me happy as well!
Cheers,
/R