I have been using the Shapelock branded version for years, and I agree, it is pretty great.
It's not like a silicone-based product, when it hardens up it feels more like HDPE or Nylon 6,6.
I've even used it for Moteino enclosures as well! But I've had limited success with certain applications, mostly for the following reasons:
1) when warm, it flows, so while you can shape it, unless you are using a mold, it continues to deform and you cannot get repeatable dimensions.
2) its flexibility changes with thickness as you are molding it, so you really have to adjust for thin parts cooling off faster than thicker parts.
3) it traps air in bubbles if you knead it and capture some air. That in itself is not so bad, but if you heat it in water, it will also trap a lot of moisture in similar bubbles. I would not want to put that next to electronic components (or not directly - if you seal things in plastic first, that may work just fine).
4) because of the above, I do not use water to heat the substance. It goes from a white color to a near-clear color when it crosses its glass transition temperature, but you do not get any further visual clue about the temperature until it begins to boil, and that occurs at a much much higher temperature. Heating it in water creates a maximum temperature at 100C so at worst you get scalded, but not using water so as not to trap water is very dangerous. It can get above 200C very easily, with no visual cue. And when you grab it, it instantly adheres to your skin, and has a very high heat capacity as well, so burns you and continues to burn you and you cannot remove it except by sacrificing some other fingers. Even if you have a handy source of cold water, all this will do is harden the outer shell, while the inner part that is adhered to you continues to burn you.
The "stickiness" of the substance seems to be parametric to temperature. I mean that against ICs and PCBs, but also against glass, and stainless steel, and of course, human skin.
As you might be able to surmise, #4 above happened to me. It was because I lost track of the time elapsed while heating. Stupid of me, I know. It just got hotter and hotter, with no visual cue. It was supposed to be just a bit warm... The result was not pretty. I still don't use water to heat the substance, but now I always check it with a non-contact infrared thermometer, you can get for $10 or $15. Even if you do use hot or boiling water, you will find that when it is uncomfortably hot but able to be handled, it will be much stickier than when closer to its transition temperature. I recommend checking the temperature no matter what you are doing.
The stickiness does change after adhesion as well - so while it will stick to glass strongly when really hot, as soon as it cools it can be peeled right off. That makes it less useful for things where you want to partially embed something in it, that doesn't have a mechanical shape that prevents slippage, especially if under load.
I'd be concerned about the polymer flowing around and under the components if applied directly, and then when/if you remove, it might cause sideways forces that exceed the trace to fiberglass adhesion force, tearing off the components.
Don't get me wrong, the stuff is great, and I have used it over and over for a lot of things where tight final dimensions are not critical. And you can sand it down after, if you need to adjust more precisely. I love the stuff. But be careful!
Please post if you come up with an excellent technique! I've clearly already disqualified myself...