Why people don't test development distributions

One of the best things about GoboLinux is the ability to have (and run!) multiple versions of software on the system. None of this: Upgrade Everything And Never Be Able to Go Back. If you upgrade a library or piece of software and it turns out to suck, you can always go back to using the one that doesn't suck. You get the best of both worlds: fast access to Shiny New Software, as well as Continuing Access to Stuff That Works.

I've even run KDE3 and KDE4 at the same time! Literally, both were running and operational in parallel. When KDE4 would inevitably crash hard, I could continue working with the KDE3 interface while KDE4 eventually raised itself from confused sloth to restart.

This does mean you have to occasionally go in and manually uninstall old libraries and software you're not using any more (by 'manually', I mean run the RemoveProgram script; you can also do it by rm-ing the files and symlinks if you want), but that is a small price to pay.