From my experience, its much more stable. Sid is "unstable" by Debian's definition, but Debian's definition of Stable is a lot more intense than most other distros.

If you want a little more stability but still rolling release, do Debian Testing. Packages are only really delayed by 2-10 days (except during release windows where they do branching). The only criteria for something getting into Testing is that it passes all tests while in Sid for multiple or all supported platforms.

But overall, Sid is fairly rock solid. If anything I think Rhino Linux should have taken Debian Sid or Testing as a source, adding all the niceties/desktop/sane defaults of Ubuntu that they like. and released that.