Just wondering what kind of effects negative values have on the signal. I know in some programs, negative values add saturation to only higher signals and things like that, but I have a feeling this negative value is just decreased saturation? Sounds good either way.

Not sure I get it. Multiplying for a negative (linear) gain?
It is just opposite phase and positive gain.
What else do you mean?

Or saturating just one side of the waveform? It is all orders harmonics plus DC offset.

so it's just less saturation effect?

For instance, in Ableton they have a dynamic tube and a Saturator which dial in negative values.

With the Tube, if you dial in a negative envelope value, then you can control where the saturation becomes present, like on just the loudest parts of the signal, so all the quiet stuff is clean, but once it reaches a threshold, it begins to distort

Oh, ok, so just a negative gain?
It attenuates the incoming signal?
So, when positive it amplifies and you get more saturation, if negative attenuates and get less saturation.
If it was saturating too much, negative gain (reducing saturation) can give you the feeling you started saturating some part of the signal, while it was over-saturated instead and you weren't hearing its component.