Was playing with the arranger with Sampler 4 set to Bass as opposed to the default drum set, and ended up doing a lot of side scrolling to find the notes I wanted. How about this for a suggestion: Each arranger gets a new mode key somewhere. Holding this mode key (or maybe toggling it) puts you in a new mode, whereby each column of the eigenharp becomes a scale of playing keys all starting on the same tonic note, and proceeding in parallel down the keyboard. You toggle on a key somewhere in each column, and that becomes the note for the corresponding column back in the arranger. You could even toggle several so that each arranger column could trigger a chord as well as a single note. Even with single notes, you can space them out along the vertical length of the Alpha, and then back in the arranger those widely spaced notes will map onto the first 5 columns, meaning much less scrolling around.
This submode would also scroll sideways, and possibly vertically as well to get to higher octaves, although that might be better done with a per-column pair of octave shift keys.
Does this make sense and sound like a good idea?