The sample and hold works very well. As I stated I build 2 that can share a trigger or can be independently triggered (using the switching capability of the 3.5 mm jack chassis). For the capacitors I found 2 types that worked well and should be easily available. I do not know which material it is made of I’m afraid. This is the type (not the value).
You can see the actual capacitors I used in the halved ic-sockets in the 2nd picture (center of the picture below the ICs).
Initially I had not included the gating bit (the 4093 logic) to the circuit, I thought I could do this by using an external trigger, but the LF needs a very short pulse (a few micro seconds), so I added this eventually which is why it is on a separate strip board.
So far I’ve used it with rather frequent triggers, and not noticed any drop in the output voltage between those which could affect the circuit that follows the S&H. I tried it with an oscillator frequency for a while given that the human ear is very sensitive to pitch changes and could not detect any whining / sinking of the pitch, so to speak.
Your and probably my mileage may vary with long periods between the pulses. So the IC socket approach may turn out to come in handy when the need arises to change the capacitors / experiment with other type capacitors.
Let me know how you fare if you are going to try this !