It's also a good way to integrate alien technologies into designs
Indeed. Especially if you're playing a scenario with self-imposed limits, like a ruin-heavy game I've been playing recently where I didn't allow myself to build jump engines or the like, instead depending entirly on a supply of jump engines and jumpgate construction modules recovered from ruins.
It does not; however, work for fighters. My Pinnaces use a particular sensor module and after scrapping the first batch of pinnaces when I went to build the next generation they did not make use of the existing stockpile of sensors. I'm not sure about other systems for fighters but they don't look for the sensors.
Funny, it worked for the grav sensors of my early survey fighter in the above game - at the time I didn't even have the ability to build them, which might have been a factor.
Sure you stockpiled the right sensor?