just came across an issue with unison voices (synth mode). It seems that the note range for the unison voices is limited to 88 keys - at least the lower limit. If you set the part octave to say -1 (or use layer transpose or osc pitch coarse) and play an 88 keyboard in the lowest octave, you'll notice that the unison voices stay at a constant pitch while the "core" voice follows the keys played correctly.
That's really annoying. It happens even when unison octave is set to +1 or +2. Of course with a part octave setting of -2, even the first 2 octaves on the keyboard are unusable with unison.
If you want to test it, it's most noticeable with hardsync set so that a higher pitch is produced. And before you ask: yes, such low ranges can be very useful. I haven't tried with sample mode, but would suspect that it's the same. Also didn't check harmonia.
A brief test showed that the actual oscillator range goes almost 6** octaves below the range of an 88 keyboard - surely unsion voices should cover the same range, no?
**) EDIT: Just to clarify - I'm aware that MIDI note range is limited and octave or transpose settings have an effect on the MIDI note# transmitted - and thus will not go below note# 0 (the low A an the keyboard is #21). As far as I can tell, that range is covered by the OSC and keytracking. Lower pitches can be achieved with OSC pitch coarse (+/- 4 octaves).