actually, I don't think it'd be much work at all.
As far as heat is concerned, not sure if it's just my JB3, but my JB3 runs really warm! Swap that HD with non-moving part should cut the heat down drastically (on paper this would appear to be the case).
As far as a "benefits" of doing this mod, well in the end you have a solid state recorder if that's of any interest (right now the JB3 is not solid state), a device generating
less heat, and a recorder that should weigh a bit less (figuratively speaking). Last time I checked but CF cards weigh at most about 1/10" the weight of a laptop hard drive.
But then that's coming from someone who's JB3 has shut completely off (one time too many, and mid show mind you) from too much heat......
For discussion's sake, if this were of no benefit, then why would others do it to a different recording device(s)?
sounds like a lot of work for very little benefit. It won't be THAT much cooler, and you will only shave a handful of grams. At the end of the day it's still a JB3!