[cks]

I highly recommend this plugin! I find it really snappy on my projects.

I haven't had the opportunity to try it on any gigantic projects, but I have found configuration files for YCM in the Chromium source tree which suggests that it scales nicely (assuming it's usable on the Chromium tree).

[McUsr]

I haven't tried it on anything but rather small projects in C: 10-15 source files/modules, but I prefer vim and ycm to XCode for coding. As a matter of fact, all other code completion thingy's I use seem a bit crappy in comparision, with the excempt of bbautocomplete.

Time to install the new beta of vim, and check out ycm! :)