I used to do quite a lot of requirements capture ... finding out in some detail what the client really wanted, not just what they thought they wanted, and the difference can be profound
+1
I would guess the developers here would do the same thing. They're aware of the desire for a built-in arpeggiator and hopefully they are aware of the arpeggiators that exist elsewhere. They also know how best to bring forth such capability in a way that leverages the other features in BiaB so that 1+1=5.
If this is taken on, I'm confident that workflow, ease of use and maximun feature considerations will be design-drivers.