In regards to voice pitch alteration for each voice; this hasn't really been discussed. I am not sure if Vince will make a hardcoded top and bottom limit for each specific voice or generically.
Personally I would like to make it specific to each voices. Depending on the individual the max lowest pitch alteration you can do before things sound awry is - 2 to -3 semitones. For Up pitch it would be + 1 semitones unless your dealing with someone who has an already deep voice in which case you might be able to go + 2 without sounding chipmunk-ish.
If we control the pitch level amounts based on what reasonable limits would be for each individual voice then we might be able to avoid detracting or annoying voice pitches.