I was a Gentoo user about 5 years ago. With Gentoo you can have both, if you only use stable packages you shouldn't broke your system. But if you are using bleeding edge packages thinks can break.
Current Gentoo user. I find the opposite. Using unstable, things just work. Sometimes package updates fail to compile but your system is still fine, and the package will get fixed eventually. Never had an update break my system on unstable. Stable often had issues, which I presume is due to devs mostly working on unstable.
