I really like this thing a lot, Great work!
Unfortunately, maybee through absent-mindedness, you've forgot to add two obvious options for the oscillator section, but I'm happy to help:
Just add a possibility to dial in some Noise for all waveforms (e.g. Shift-Timbre) and, while you're at it, add a Squarewave Sub-Oscillator (e.g. Shift-Wave).
Some of the Waves and oscillator models lack a bit of content in certain frequencies and I think this would help to beef them up.
Thanks!