Until I started into the realm of AF bodies sometime back in the early 1980s, I had an FE-2, FM-2n and a couple of FAs. They replaced by "magic meter" Nikkormat EL/EL2 cameras that I used and loved for long-exposures where I didn't want to do the math for the exposure. That generation of automation took a silver-oxide battery that during the silver speculation and eventual crash that nearly lead to the end of film photography and skyrocketed the costs of the batteries to a ridiculous price.
The FM/FE series helped since they could run on smaller alkaline batteries and the main reason for the -2 series was their 1/250th flash sync which with a TTL flash worked wonders for fill-in flash.
The FM-2n was the last of the three different bodies I purchased and used as I wanted something for back-up that wasn't battery dependent for running the shutter when the batteries died and I needed more than B & 1/250/x-sync that the former would revert. It was the fail-safe body!
FE-2 and FM-2 served me well for many years and were great to use because of their size and weight while rafting for two weeks down the Colorado River. They served me well for another few years as I transitioned into AF and traded most of the off.
I kept the FM-2n as back-up for the AF bodies but by the time it was time to sell it, it had little value. Same thing happened to many of the AF bodies. In the years since, I've been given additional FM/FE variations along with many other pre-AF bodies that would have been tossed. Once things settle down in the world I hope to find good homes for them with the next generation to rediscover film. I only wish I had the time and energy to put them to use myself!