I'm not sure Rocket is Rust's leading framework. It certainly looks nicer than some, but still requires Rusts's nightly build, IIRC. I'm sure that means a lot of people opt for something like actix-web, or just fall back on hyper. My impression is that Rust's users are pretty widely spread across the frameworks that exist, so it may not be that you picked the wrong framework, but that isn't really a "leading" framework yet.
Someone might jump in with better info on the usage rates than me and correct me though, since this is mostly observational on my part. :)
http://www.arewewebyet.org/topics/frameworks/
Also just for fun I did try out Iron, Actix-web, and Gotham, and they all put out pretty similar figures (iron&gotham bit smaller, actix-web bit bigger). I do feel like Rocket is being a good representative example here.
That being said, I wouldn't be surprised if Rocket would be bit more feature-packed than Jester.
Thanks for the leg work. :)
I'm not saying we should draw conclusions based on just this comparison. But it is an additional nugget of information and an invitation for others to also give Nim a try when targeting embedded systems :)