Gentoo user here.
Yeah, rolling my own kernel, it's really fun to configure it with yourself and I think the main benefit of its, you don't have unnecessary firmwares, kernel options etc like pre-compiled binary kernels of distros. Furthermore, you may patch it with BFS, tuxonice or etc for performance improvements! Especially ck patch set for BFS.
Gentoo is stable if you know how to handle it. This is quite easy;
- Use eix for sync and package search.
- Do no update it very often, once in a week is good.
- Mask is your saviour!
- Read news.
My Gentoo is unstable version. But it never failed me.