Your knowledge about Emacs was outdated then. And what make you think that Emacs cannot use Clang and LLVM? Currently, there's already rtags that uses Clang for live analysis: https://github.com/Andersbakken/rtags. Here are some nice features that Emacs provide:

- Powerful automatic indentation: https://raw.githubusercontent.com/Bruce-Connor/aggressive-in.... It does not only indent the current line, but the whole Semantic context around your cursor.

- Live grep: http://tuhdo.github.io/static/live_grep.gif

- Access to a list of project with a few key strokes: http://tuhdo.github.io/static/helm-projectile/helm-projectil...

- Quickly access any file in your project, as large as Linux kernel, instantly, regardless of where you are in the project, and within a few keystrokes: http://tuhdo.github.io/static/helm-projectile/helm-projectil....

- Jump to any file depends on context, even if the file path is in a plain ASCII text file: http://tuhdo.github.io/static/helm-projectile/helm-projectil...

- Copy files from anywhere to anywhere: http://tuhdo.github.io/static/helm-projectile/helm-projectil....

- Delete files anywhere; files are always at your finger tip to do whatever with them: http://tuhdo.github.io/static/helm-projectile/helm-projectil....

- Switch between other files with same names but different extensions: http://tuhdo.github.io/static/helm-projectile/helm-projectil.... Work not only for C/C++ but other languages, and is customizable. You don't have to configure anything, like adding include paths for the command to search. Everything is automatic. Just use it as it is.

- Jump to tag definition, from Emacs's own parser or external parser like GNU Global: http://tuhdo.github.io/static/c-ide/helm-gtags-jump-dwim.gif

- Jump to any definition from a list of definitions in source tree, even for Linux kernel: http://tuhdo.github.io/static/c-ide/helm-gtags-select.gif

- Jump up to parent: http://tuhdo.github.io/static/c-ide/senator-go-to-up-referen....

- Do you like outline tree?: http://tuhdo.github.io/static/c-ide/sr-speedbar.gif

- Interactive outline tree: http://tuhdo.github.io/static/c-ide/helm-semantic-or-imenu-w...

- Easily move back and forth using the interactive outline tree: http://tuhdo.github.io/static/part3/helm-semantic-or-imenu-2...

- References retrieved from its Emacs internal parser: http://tuhdo.github.io/static/c-ide/semantic-symref.gif.

- Beautiful compile output: http://tuhdo.github.io/static/c-ide/compilation-compile.gif

- Frontend support for GDB: http://tuhdo.github.io/static/c-ide/gdb-many-windows.gif

- Code completion: http://tuhdo.github.io/static/c-ide/semantic-boost-demo.gif.

- Open man page for symbol at cursor: http://tuhdo.github.io/static/part3/helm-man-woman.gif.

- Emacs open 39MB C file: http://tuhdo.github.io/static/performance.gif

- Emac opens multi-gigabtye file: http://www.emacswiki.org/VLF

- Emacs is a bit torrent client: https://bitbucket.org/ukaszg/aria2-mode/

You can see more demos in:

+ Emacs Mini Manual: http://tuhdo.github.io/emacs-tutor.html
+ C/C++ Development Environment for Emacs: http://tuhdo.github.io/c-ide.html
+ A Package in a league of its own: Helm: http://tuhdo.github.io/helm-intro.html
+ Exploring large projects with Projectile and Helm Projectile: http://tuhdo.github.io/helm-projectile.html

Note that in the demos you may see me type in the commands. You can think of it like the start menu in Windows, but actually those commands can be executed quickly with a shortcut. I type in the commands for demonstration purpose to Emacs users.

Those demos are just tip of the iceberg.