HSx (M) might be more useful here. A couple of directions you can take with momentary switching:
- OFF for your base Decay value – Freeze for ON.
- Freeze as the default OFF (dry signal passes). Decay value for ON.
One advantage to the latter is that you ‘sample’ the reverb when you press the switch, and the Freeze will sustain upon switch release. Another smooth option substitutes an expression pedal. Confine the full sweep range to a high Decay value, Infinite, and Freeze. Then gradually mix through them with your foot.
No SuperEgo-like auto-latching / glide (unless you count the Infinite buildup of input notes). But you did give me a few ideas to explore, using the Freeze options in PolyFlex / Polyphony.
