Except with Gentoo, you have to install all the header files for every library you use, which easily outweighs any benefit you get from not having to install certain locales, etc. When I saw that my 2GB install of Gentoo was equivalent to a 500MB install of Ubuntu I abandoned it.
Also, if you are a developer, do you really want to be a one man/woman IT show just to get your laptop up and running? Gentoo is a great learning distro that is slightly more abstracted away than Linux From Scratch, but that's where its usefulness ends. Doing a proper "compile newer version of GCC, then recompile GCC with it, then recompile GCC again" voodoo is just tiresome after the first time. Yes you may lose some performance, but chances are your time is worth way more than what the setup takes.