The problem with adding extra Pitch Bend range is two fold : it pushes the overall range of the oscillators. Currently there is potentially 8octaves of notes plus a range of C1 to C5 oscillator pitch. I think if you add a further 2 octave of pitch bend youre at 15 octaves!? Clearly that doesn't work without compromise. Also the p6 pitchbend circuit has a finite mechanical/electrical/electronic resolution. Driven largely by the pot quality and ADC. The possible range of +\- 8k (14bits of data) of the midi message is probably fine but most devices don't fully encode to that resolution especially if you're using an onboard 10bit ADC, I doubt that's +\- 1bit accurate. So going beyond +\- 1 octave may produce quantised pitch steps.
Thanks for the thoughtful reply. A few return comments to keep the tech talk going (I love the tech talk!)...
Regarding # of octaves: Obviously, when using my ribbon, I have no desire to go to the 15th octave, so whether the synth is able to go there (or not) won't be a problem that I would encounter. But, you're right, the synth needs to be able to handle that case without locking up. I have already perceived that they Prophet 6 limits the highest pitch that you can get. I believe that if the keyboard is set to the highest Transpose setting and if the oscillator is set to the highest octave, all of the keys in the top octave play the same pitch. So, the Prophet 6 already has a limit, and it's fine with me.
Regarding the finite resolution, I agree that the physical pitch bend wheel will likely end up sounding quantized if they enabled a +/- two octave bend. That's not really an issue for me...I've got whatever resolution I've got (which may or may not be sufficient), but it doesn't matter whether that resolution is spread across many notes + small bends or if it is spread across one note + big bends. My semi-tones per bits is the same either way. With a ribbon, I'd prefer it to be spread as one note + big bend so that I don't have to retrigger a new note in the middle of a slide, simply because I've run out of bend.
Thanks for your interest!
Chip