The current 5.11 is over a year old, and eas mainly based on etch, which was labeled "unstable" at the time. I Installed a lot of etch then and was very happy with it. Now that etch is considered the stable version of Debian, I expect that my next Debian install will be the new unstable version, as the stable version tends to be too old for a lot of users. However, if it supports your hardware and you don't have other issues with it then you may be happy with etch. One nice thing about Debian, and Linux in general, is that it is rather simple to install different distros and see how they fit your needs. I've done many net installs of Debian just for the experience or to compare different options.

While Knoppix is Debian based, you might find better hardware support with some other distros. I'm not a hugh ubuntu fan myself but a lot of people are switching to it because it tends to support new hardware faster than Debian. And Mandriva is also worth a look if you're shoping for particular hardware support.