Hi

> So the Quad ADSR module can generate audio range signal as a pseudo
> LFO with the end of decay out patched to the ADSR's own gate input.
> What are the drawbacks to using it as an audio/LFO source

The main drawback for the usage as LFO is, that the frequency depends on
the setting of each time related parameter (attack, decay, release). you
cannot modify the waveform (=envelope shade) without touching the
frequency of the LFO.

> I know that
> the signal is always above 0 volts because it's an ADSR, right ...

I never felt that as an disadvantage. In the opposite, I often wish, the
LFO would be like an ADSR always above 0 volts.

Florian