When comparing Eclipse Che vs Femto Emacs, the Slant community recommends Eclipse Che for most people. In the question“What are the best open-source text editors for programming?” Eclipse Che is ranked 20th while Femto Emacs is ranked 37th. The most important reason people chose Eclipse Che is:
Built-in terminal with root access so you can make changes to your running machines. Being able to SSH into the workspace so you can use a desktop IDE is handy.
Specs
Ranked in these QuestionsQuestion Ranking
Pros

Pro SSH + terminal
Built-in terminal with root access so you can make changes to your running machines. Being able to SSH into the workspace so you can use a desktop IDE is handy.

Pro Custom commands
You can package up custom commands with your workspace and then use them (or share them) with everyone else.

Pro Docker runtimes
You can choose from pre-configured environments for Java, Javascript, C++, PHP, C#, etc., or you can define your own by dropping in a Dockerfile - makes it easy for simple and complex projects.
Pro GIT and SVN VCS support
Projects can be easily imported from any Git or Svn repository hosting service.
Pro Reproducible environment

Pro Portable workspaces
The workspace in Che includes project sources, IDE and the runtime. So if you hand your Che workspace definition to another user and they execute it they will get everything they need to build, run and debug the project.
Also the runtime is in a Docker container so it will work even if the second user is on a different OS than the original user who shared their workspace with them.

Pro Previews
Che does a nice job to automatically map the service:port running in the Docker container (e.g. tomcat on 8080) to the Docker port it actually uses (something in the ephemeral range). You never need to figure that out - it's just made available when you run your server.
Pro Merge tool for VCS

Pro Open-source
Pro Well documented
A long and well written tutorial teaches how to program in femtolisp and write extensions for Femto Emacs.
Pro Highly compatible with Emacs
If you know Emacs, you can start using Femto Emacs immediately.
Pro Very small footprint
The size of the executable file and the femtolisp library add up to only 500 k. The C source code is also small and well documented, so one can easily modify it. You can also use the source code to learn how to program a text editor.
Pro Very fast startup time
For small files, Femto Emacs starts up faster than emacs or vim.
Cons
Con Slow runtime
Online IDE is much slower than desktop one.
Con No syntax coloring for Latex
The distribution comes with syntax coloring examples for many languages, like Haskell, C, Lisp, Python, etc. However, there is no scheme for Latex. If you need syntax coloring for Latex, you will need to add your own color scheme.
Con Source distribution only
Femto Emacs is distributed only in source form. Therefore, you need to install ncurses, gcc and compile it with make and make install. There is no binary distribution. If you want mouse support, you need to program it in femtolisp or in C. This should not be a problem if you are a programmer, but can become an issue if you don't know Lisp or C. If you want to use femtolisp on Windows, you will need mingw and ncurses.
