Hi

> solution #1: universal vactrol module across the Release potentiometer
> solution #2: VC switch across the Release potentiometer (e.g. A-150)

Four both solutions I suggest not to short the Release pot completely,
but switch a smaller resistor value or a second potentiometer in
parallel, so there is still control for a shorter release time.

Another nice possibility would be: the switch should select whether the
release-time is determined by the decay-potentiometer or the
release-potentiometer. I am a big fan of the envelopes used in the moog
prodigy or polymoog, which do not know about a separate release, but
simply have a switch that enables release or not. For monophonic synths
it is perfect for classic sequences, for polyphonic synths it works like
the pedal of a piano.

An envelope which provides an additional alternative release-time would
be perfect.

Florian